Biblically speaking, we know that when we have believed on the Son (which is the will of the Father) we have been born again/born of God.
Well, the Bible appears to indicate that we are born again when we are baptized.
Now there was a man of the Pharisees named Nicodemus, a ruler of the Jews. 2 This man came to Jesus by night and said to him, “Rabbi, we know that you are a teacher come from God, for no one can do these signs that you do unless God is with him.” 3 Jesus answered him, “Truly, truly, I say to you, unless one is born again he cannot see the kingdom of God.” 4 Nicodemus said to him, “How can a man be born when he is old? Can he enter a second time into his mother's womb and be born?” 5 Jesus answered, “Truly, truly, I say to you, unless one is born of water and the Spirit, he cannot enter the kingdom of God. 6 That which is born of the flesh is flesh, and that which is born of the Spirit is spirit. 7 Do not marvel that I said to you, 'You must be born again.’ 8 The wind blows where it wishes, and you hear its sound, but you do not know where it comes from or where it goes. So it is with everyone who is born of the Spirit.”
I do not think you see the word "born again" mentioned in Scripture with respect to belief, but please correct me if I am wrong.
The new creation that we are, cannot and does not sin. There is no longer any condemnation for those in Christ Jesus. The wrath of God does not remain upon us, because of what Christ has done for us. We have passed from death (being dead in our sins) to life (given to us through the Son).
Sure, but just because you are in Christ today, does not mean that you will be in Christ tomorrow. If you go out and murder 20 people tomorrow, and become an atheist, would you remain in Christ?
So, would the "sin that leads to death" not be rejecting the Saviour? After all, it is rejecting Him that leaves a person subject to the wrath of God, because the wages of sin (all sin, which is missing the mark or falling short of God's standard of absolute perfection) is death, but the gift of God is eternal life, in His Son, Jesus. It seems clear to me (Biblically) that the "sin that leads to death" is rejecting Christ, Who, Scripture is clear, is the ONLY Way to be saved.
Absolutely. Rejecting Jesus as Lord and Savior (for example, becoming an atheist) would be a sin that leads to death. But we also reject Jesus as Lord and Savior when we commit other mortal sins.
Anyway, I do not see how those verses support the Catholic doctrine of "mortal" and "venial" sins. What I do see in Scripture, is that ALL sin is "mortal", and without Christ, we will reap the wages of sin (death).
People who are baptized are no longer children of wrath, but become children of God. God, like any merciful and loving father, treats his children with grace. This means that we do not have to be perfect. God does not treat his children like a judge who demands strict adherence to every letter of the law. A merciful and loving father would not send one of his children to eternal fire for telling a little white lie.
But just because we are children of God, does not mean that we can do any and all sins, and expect to receive our inheritance from our father. A child can lose his inheritance. If your son has a test, studies hard, and gets say a C+ on the exam, you are going to still take him out to a baseball game, because you are a loving parent. You are not going to say, "Well, you did not get a 100% so I am putting you on punishment". On the other hand, if your son completely goofs off and says "Screw that test, I do not even care that my mum asked me to study for it" and does not even try at all and gets an F, you are not going to take him to the baseball game, even though he is your son and you love him. You are going to put him on punishment. This is kind of the way that it works for people who have been baptized into Christ. You do not have to be perfect, but nor can you do anything and everything.
That is my analogy, at least. I would need to search for some specific Scripture to back it up.
If you take a re-read through the New Testament, you will see verses in almost every book that warn against falling from grace, because of sin. I have provided a few already I think in this thread, but here are a few more for your consideration:
For if we go on sinning deliberately after receiving the knowledge of the truth, there no longer remains a sacrifice for sins, 27 but a fearful expectation of judgment, and a fury of fire that will consume the adversaries. 28 Anyone who has set aside the law of Moses dies without mercy on the evidence of two or three witnesses. 29 How much worse punishment, do you think, will be deserved by the one who has trampled underfoot the Son of God, and has profaned the blood of the covenant by which he was sanctified, and has outraged the Spirit of grace? 30 For we know him who said, “Vengeance is mine; I will repay.” And again, “The Lord will judge his people.” 31 It is a fearful thing to fall into the hands of the living God.
Not above that St. Paul refers to "we" (which includes himself, a believer). Note also that that the people he refers to have been sanctified by the blood of the covenant, also indicating that they are saved. Paul seems to teach that if these people go on sinning deliberately, Jesus's sacrifice on the cross will not apply to them.
But I say, walk by the Spirit, and you will not gratify the desires of the flesh. 17 For the desires of the flesh are against the Spirit, and the desires of the Spirit are against the flesh, for these are opposed to each other, to keep you from doing the things you want to do. 18 But if you are led by the Spirit, you are not under the law. 19 Now the works of the flesh are evident: sexual immorality, impurity, sensuality, 20 idolatry, sorcery, enmity, strife, jealousy, fits of anger, rivalries, dissensions, divisions, 21 envy, drunkenness, orgies, and things like these. I warn you, as I warned you before, that those who do such things will not inherit the kingdom of God. 22 But the fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faithfulness, 23 gentleness, self-control; against such things there is no law. 24 And those who belong to Christ Jesus have crucified the flesh with its passions and desires.
25 If we live by the Spirit, let us also keep in step with the Spirit. 26 Let us not become conceited, provoking one another, envying one another.