First of all, although I think you have valid questions, they cannot be answered simply with just a few posts. First of all, it requires faith to believe and that point is not negotiable. You either believe the Gospel of Christ or you don't.
If you believe the Gospel, then you believe the testimony given about Him. And if you believe the testimony about Him, then you would believe the rest of the Bible as being authoritative because what is written about Christ, the Word, is that HE is the Word, All things were created through Him and by Him and that He comes from the Father. That He was given authority. That His authority comes from the Father.
That He promised the Holy Spirit to us who would teach us and declare to us ALL things. That is how we can say that the Scriptures are True and are no falsehood. That is how we can testify that these Scriptures are the Word of God and are true. That is why they have authority. But it is only to those that believe, that can see these things. Whose eyes and ears have been opened. Do you believe? OR are you wanting a debate. I don't debate because it is fruitless.
John 1:1 IN THE beginning [before all time] was the Word (Christ), and the Word was with God, and the Word was God Himself.
So, when is the first record of the Word? Which John says is Christ?
Gen 1:3 And God said, Let there be light; and there was light.
That is the first written record of God's Words.
John 1:2 He was present originally with God.
John 1:3 All things were made {and} came into existence through Him; and without Him was not even one thing made that has come into being.
John 1:4 In Him was Life, and the Life was the Light of men.
John 1:5 And the Light shines on in the darkness, for the darkness has never overpowered it [put it out or absorbed it or appropriated it, and is unreceptive to it].
Gen 1:4 And God saw that the light was good (suitable, pleasant) {and} He approved it; and God separated the light from the darkness.
You could take this passage as literal and symbolic at the same time. The point I am trying to make is that when God opens His mouth, His expression is the Word, Christ. You will find that principle throughout the Word of God, OT and NT.
John 1:6 There came a man sent from God, whose name was John.
John 1:7 This man came to witness, that he might testify of the Light, that all men might believe in it [adhere to it, trust it, and rely upon it] through him.
John 1:8 He was not the Light himself, but came that he might bear witness regarding the Light.
John 1:9 There it was--the true Light [was then] coming into the world [the genuine, perfect, steadfast Light] that illumines every person.
John 1:10 He came into the world, and though the world was made through Him, the world did not recognize Him [did not know Him].
Gen 1:3 And God said, Let there be light; and there was light.
Gen 1:6 And God said, Let there be a firmament [the expanse of the sky] in the midst of the waters, and let it separate the waters [below] from the waters [above].
Gen 1:9 And God said, Let the waters under the heavens be collected into one place [of standing], and let the dry land appear. And it was so.
Gen 1:11 And God said, Let the earth put forth [tender] vegetation: plants yielding seed and fruit trees yielding fruit whose seed is in itself, each according to its kind, upon the earth. And it was so.
Gen 1:14 And God said, Let there be lights in the expanse of the heavens to separate the day from the night, and let them be signs {and} tokens [of God's provident care], and [to mark] seasons, days, and years,
Gen 1:20 And God said, Let the waters bring forth abundantly {and} swarm with living creatures, and let birds fly over the earth in the open expanse of the heavens.
Gen 1:24 And God said, Let the earth bring forth living creatures according to their kinds: livestock, creeping things, and [wild] beasts of the earth according to their kinds. And it was so.
Gen 1:26 God said, Let Us [Father, Son, and Holy Spirit] make mankind in Our image, after Our likeness, and let them have complete authority over the fish of the sea, the birds of the air, the [tame] beasts, and over all of the earth, and over everything that creeps upon the earth.
John 1:11 He came to that which belonged to Him [to His own--His domain, creation, things, world], and they who were His own did not receive Him {and} did not welcome Him.
John 1:12 But to as many as did receive {and} welcome Him, He gave the authority (power, privilege, right) to become the children of God, that is, to those who believe in (adhere to, trust in, and rely on) His name--
John 1:13 Who owe their birth neither to bloods nor to the will of the flesh [that of physical impulse] nor to the will of man [that of a natural father], but to God. [They are born of God!]
John 1:14 And the Word (Christ) became flesh (human, incarnate) and tabernacled (fixed His tent of flesh, lived awhile) among us; and we [actually] saw His glory (His honor, His majesty), such glory as an only begotten son receives from his father, full of grace (favor, loving-kindness) and truth.
John 1:15 John testified about Him and cried out, This was He of Whom I said, He Who comes after me has priority over me, for He was before me. [He takes rank above me, for He existed before I did. He has advanced before me, because He is my Chief.]
John 1:16 For out of His fullness (abundance) we have all received [all had a share and we were all supplied with] one grace after another {and} spiritual blessing upon spiritual blessing {and} even favor upon favor {and} gift [heaped] upon gift.
John 1:17 For while the Law was given through Moses, grace (unearned, undeserved favor and spiritual blessing) and truth came through Jesus Christ.
John 1:18 No man has ever seen God at any time; {the only} {unique Son}, {or} the only begotten God, Who is in the bosom [in the intimate presence] of the Father, He has declared Him [He has revealed Him and brought Him out where He can be seen; He has interpreted Him and He has made Him known].
So, Christ in the flesh, is the interpretation of Christ the Word.
Matt 7:29 For He was teaching as {One} Who had [and was] authority, and not as [did] the scribes.
Matt 9:6 But in order that you may know that the Son of Man has authority on earth to forgive sins {and} remit the penalty, He then said to the paralyzed man, Get up! Pick up your sleeping pad and go to your own house.
Matt 28:18 Jesus approached and, breaking the silence, said to them, All authority (all power of rule) in heaven and on earth has been given to Me.
Mark 1:22 And they were completely astonished at His teaching, for He was teaching as One Who possessed authority, and not as the scribes.
John 2:13 Now the Passover of the Jews was approaching, so Jesus went up to Jerusalem.
John 2:14 There He found in the temple [enclosure] those who were selling oxen and sheep and doves, and the money changers sitting there [also at their stands].
John 2:15 And having made a lash (a whip) of cords, He drove them all out of the temple [enclosure]--both the sheep and the oxen--spilling {and} scattering the brokers' money and upsetting {and} tossing around their trays (their stands).
John 2:16 Then to those who sold the doves He said, Take these things away (out of here)! Make not My Father's house a house of merchandise (a marketplace, a sales shop)!
John 2:17 And His disciples remembered that it is written [in the Holy Scriptures], Zeal (the fervor of love) for Your house will eat Me up. [I will be consumed with jealousy for the honor of Your house.]
John 2:18 Then the Jews retorted, What sign can You show us, seeing You do these things? [What sign, miracle, token, indication can You give us as evidence that You have authority and are commissioned to act in this way?]
John 2:19 Jesus answered them, Destroy (undo) this temple, and in three days I will raise it up again.
John 2:20 Then the Jews replied, It took forty-six years to build this temple (sanctuary), and will You raise it up in three days?
John 2:21 But He had spoken of the temple which was His body.
John 5:26 For even as the Father has life in Himself {and} is self-existent, so He has given to the Son to have life in Himself {and} be self-existent.
John 5:27 And He has given Him authority {and} granted Him power to execute (exercise, practice) judgment because He is a Son of man [very man].
John 7:17 If any man desires to do His will (God's pleasure), he will know (have the needed illumination to recognize, and can tell for himself) whether the teaching is from God or whether I am speaking from Myself {and} of My own accord {and} on My own authority.
John 8:28 So Jesus added, When you have lifted up the Son of Man [on the cross], you will realize (know, understand) that I am He [for Whom you look] and that I do nothing of Myself (of My own accord or on My own authority), but I say [exactly] what My Father has taught Me.
1 John 5:6 This is He Who came by (with) water and blood [His baptism and His death], Jesus Christ (the Messiah)--not by (in) the water only, but by (in) the water and the blood. And it is the [Holy] Spirit Who bears witness, because the [Holy] Spirit is the Truth.
1 John 5:7 So there are three witnesses {in heaven: the Father, the Word and the Holy Spirit, and these three are One;}
1 John 5:8 {and there are three witnesses on the earth:} the Spirit, the water, and the blood; and these three agree [are in unison; their testimony coincides].
1 John 5:9 If we accept [as we do] the testimony of men [if we are willing to take human authority], the testimony of God is greater (of stronger authority), for this is the testimony of God, even the witness which He has borne regarding His Son.
1 John 5:10 He who believes in the Son of God [who adheres to, trusts in, and relies on Him] has the testimony [possesses this divine attestation] within himself. He who does not believe God [in this way] has made Him out to be {and} represented Him as a liar, because he has not believed (put his faith in, adhered to, and relied on) the evidence (the testimony) that God has borne regarding His Son.
1 John 5:11 And this is that testimony (that evidence): God gave us eternal life, and this life is in His Son.
1 John 5:12 He who possesses the Son has that life; he who does not possess the Son of God does not have that life.
1 John 5:13 I write this to you who believe in (adhere to, trust in, and rely on) the name of the Son of God [in the peculiar services and blessings conferred by Him on men], so that you may know [with settled and absolute knowledge] that you [already] have life, yes, eternal life.
John 15:25 But [this is so] that the word written in their Law might be fulfilled, They hated Me without a cause.
John 15:26 But when the Comforter (Counselor, Helper, Advocate, Intercessor, Strengthener, Standby) comes, Whom I will send to you from the Father, the Spirit of Truth Who comes (proceeds) from the Father, He [Himself] will testify regarding Me.
John 15:27 But you also will testify {and} be My witnesses, because you have been with Me from the beginning.
John 16:7 However, I am telling you nothing but the truth when I say it is profitable (good, expedient, advantageous) for you that I go away. Because if I do not go away, the Comforter (Counselor, Helper, Advocate, Intercessor, Strengthener, Standby) will not come to you [into close fellowship with you]; but if I go away, I will send Him to you [to be in close fellowship with you].
John 16:8 And when He comes, He will convict {and} convince the world {and} bring demonstration to it about sin and about righteousness (uprightness of heart and right standing with God) and about judgment:
John 16:9 About sin, because they do not believe in Me [trust in, rely on, and adhere to Me];
John 16:10 About righteousness (uprightness of heart and right standing with God), because I go to My Father, and you will see Me no longer;
John 16:11 About judgment, because the ruler (evil genius, prince) of this world [Satan] is judged {and} condemned {and} sentence already is passed upon him.
John 16:13 But when He, the Spirit of Truth (the Truth-giving Spirit) comes, He will guide you into all the Truth (the whole, full Truth). For He will not speak His own message [on His own authority]; but He will tell whatever He hears [from the Father; He will give the message that has been given to Him], and He will announce {and} declare to you the things that are to come [that will happen in the future].
John 16:14 He will honor {and} glorify Me, because He will take of (receive, draw upon) what is Mine and will reveal (declare, disclose, transmit) it to you.
1 John 5:6 This is He Who came by (with) water and blood [His baptism and His death], Jesus Christ (the Messiah)--not by (in) the water only, but by (in) the water and the blood. And it is the [Holy] Spirit Who bears witness, because the [Holy] Spirit is the Truth.
1 John 5:7 So there are three witnesses {in heaven: the Father, the Word and the Holy Spirit, and these three are One;}
1 John 5:8 {and there are three witnesses on the earth:} the Spirit, the water, and the blood; and these three agree [are in unison; their testimony coincides].
1 John 5:9 If we accept [as we do] the testimony of men [if we are willing to take human authority], the testimony of God is greater (of stronger authority), for this is the testimony of God, even the witness which He has borne regarding His Son.
1 John 5:10 He who believes in the Son of God [who adheres to, trusts in, and relies on Him] has the testimony [possesses this divine attestation] within himself. He who does not believe God [in this way] has made Him out to be {and} represented Him as a liar, because he has not believed (put his faith in, adhered to, and relied on) the evidence (the testimony) that God has borne regarding His Son.
1 John 5:11 And this is that testimony (that evidence): God gave us eternal life, and this life is in His Son.
1 John 5:12 He who possesses the Son has that life; he who does not possess the Son of God does not have that life.
1 John 5:13 I write this to you who believe in (adhere to, trust in, and rely on) the name of the Son of God [in the peculiar services and blessings conferred by Him on men], so that you may know [with settled and absolute knowledge] that you [already] have life, yes, eternal life.