Yes the Bible does teach once saved always saved with such scripture as
John 3:14-18 (NKJV)
14 And as Moses lifted up the serpent in the wilderness, even so must the Son of Man be lifted up,
15 that whoever believes in Him should not perish but have eternal life. 16 For God so loved the world that He gave His only begotten Son,
that whoever believes in Him should not perish but have everlasting life. 17 For God did not send His Son into the world to condemn the world,
but that the world through Him might be saved.
18
He who believes in Him is not condemned; but he who does not believe is condemned already, because he has not believed in the name of the only begotten Son of God.
John 10:28-30
28 And I give them eternal life, and they shall never perish; neither shall anyone snatch them out of My hand. 29 My Father, who has given them to Me, is greater than all; and no one is able to snatch them out of My Fathers hand. 30 I and My Father are one.
I love that part because it says that first they have eternal life and will never perish and then it says that no on is able to take them and not only are you in His (Christ) hands, but His hands are in the Fathers hands and no one can take anything from His Father so you're double protected.
Other scriture to support once saved always saved are Romans 8:38-39, Ephesians 4:30, and Jude 24, among others.
And now as far as some of those scriptures that people want to us the support "losing your salvation". That have always been taken out of context. Always read the whole chapter before making a decision about what a certain scripture says.
The way the Bible says thing about lets say Mark 3:29 (which is a favorite among those that do not believe once saved always saved)
29 but he who blasphemes against the Holy Spirit never has forgiveness, but is subject to eternal condemnation
Seems to be pretty straight forward right? If you blashpeme God you go to hell... ok well now lets look at Mark 3:28-30
28 Assuredly, I say to you, all sins will be forgiven the sons of men, and whatever blasphemies they may utter; 29 but he who blasphemes against the Holy Spirit never has forgiveness, but is subject to eternal condemnation 30 because they said, He has an unclean spirit.
First Jesus said that all your sins will be forgiven (by beliving in Him) but they that blaspheme the holy spirit will never have forgivness because they have an unclean spirt. If we could look at the Greek we would see that the way that verse 29 is written is a perfect tense which mean it would be better written he who blasphemes and continues to blaspheme the Holy Spirit. It is a lifestyle and one that a true Christian could never live according to 2 Corinthians 5:17
17 Therefore, if anyone
is in Christ,
he is a new creation; old things have passed away; behold, all things have become new.
Now just because we're saved forever doesn't mean we can continue in sin according to Romans 6:1-4 (NKJV)
1 What shall we say then? Shall we continue in sin that grace may abound?
2 Certainly not! How shall we who died to sin live any longer in it?
3 Or do you not know that as many of us as were baptized into Christ Jesus were baptized into His death?
4 Therefore we were buried with Him through baptism into death, that just as Christ was raised from the dead by the glory of the Father, even so we also should walk in newness of life.
So I hope that this helps your faith and Christian life.
