Eternal Security or Once Saved Always Saved is Absolutely True. The Holy Bible has many verses or passages that prove this. Here are just a few. There are many more.
Jesus Christ who is God said:
Verily, verily, I say unto you, He that believeth on me hath everlasting life.
If someone has everlasting life, then they could never be damned. If not, they did not have everlasting life but potentially had everlasting life. The verse would say, “might have everlasting life.” Jesus Christ, who is God, would not lie especially with the double verily.
Jesus also said:
14 And as Moses lifted up the serpent in the wilderness, even so must the Son of man be lifted up:
15 That whosoever believeth in him should not perish, but have eternal life.
16 For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life.
17 For God sent not his Son into the world to condemn the world; but that the world through him might be saved.
18 He that believeth on him is not condemned: but he that believeth not is condemned already, because he hath not believed in the name of the only begotten Son of God.
Verse 15 and 16 say the same thing and by the same logic prove eternal security. Both also emphatically claim, “should not perish” which again proves eternal security. In verse 18, Jesus Christ says that they are not condemned. All again prove eternal security.
Jesus Christ also said:
25 Jesus said unto her, I am the resurrection, and the life: he that believeth in me, though he were dead, yet shall he live:
26 And whosoever liveth and believeth in me shall never die. Believest thou this?
In verse 26, Jesus Christ said that they shall never die. Surely you believe God.
Paul, the apostle of the Gentiles, wrote:
And grieve not the Holy Spirit of God, whereby ye are sealed unto the day of redemption.
If your sealed till the day of redemption, you could not be damned.
In the following verse, Jesus says He is with the saved and will never leave them. How could they ever go to hell?
Let your conversation be without covetousness; and be content with such things as ye have: for he hath said, I will never leave thee, nor forsake thee.
Jesus Christ the Lord also said:
28 And I give unto them eternal life; and they shall never perish, neither shall any man pluck them out of my hand.
29 My Father, which gave them me, is greater than all; and no man is able to pluck them out of my Father's hand.
30 I and my Father are one.
If someone has “eternal life,” then they could never be damned. If not, they did not have eternal life but potentially had eternal life. Jesus Christ, who is God, would not lie. Again Jesus Christ is emphatic that “they shall never perish.” Obviously no man can pluck them out of Jesus’ hand or His Father’s hand.
The apostle John wrote the following. How can you know that you have eternal life if it is only a maybe?
1 John 5:13
These things have I written unto you that believe on the name of the Son of God; that ye may know that ye have eternal life, and that ye may believe on the name of the Son of God.
The next passage, written by Paul, the apostle of the Gentiles, says, “are saved,” not might be saved.
8 For by grace are ye saved through faith; and that not of yourselves: it is the gift of God:
9 Not of works, lest any man should boast.
Potentially damned could not be salvation as written by Paul in the following passage.
For I am not ashamed of the gospel of Christ: for it is the power of God unto salvation to every one that believeth; to the Jew first, and also to the Greek.
The following words spoken by Jesus Christ again prove once saved always saved.
Verily, verily, I say unto you, He that heareth my word, and believeth on him that sent me, hath everlasting life, and shall not come into condemnation; but is passed from death unto life.
Before the rapture, for those that are saved by the blood of the Lord Jesus Christ, there are only 2 possibilities and only one outcome. If they die before the rapture, they get a glorified body and are forever with the Lord. If they are alive at the rapture, they get a glorified body and are forever with the Lord.
2 Corinthians 5:8
We are confident, I say, and willing rather to be absent from the body, and to be present with the Lord.
1 Thessalonians 4:15-17
15 For this we say unto you by the word of the Lord, that we which are alive and remain unto the coming of the Lord shall not prevent them which are asleep.
16 For the Lord himself shall descend from heaven with a shout, with the voice of the archangel, and with the trump of God: and the dead in Christ shall rise first:
17 Then we which are alive and remain shall be caught up together with them in the clouds, to meet the Lord in the air: and so shall we ever be with the Lord.
The above sampling absolutely proves that eternal security (once saved always saved) is absolutely true. They are emphatic and quite clear. Since the Holy Bible has no contradictions, anything that you think shows otherwise is just your mistaken interpretation. Many people assume a passage is talking about salvation/damnation when it is not. This is usually done by taking the verse out of context, assuming meanings of words with false definitions and doctrines, ignoring what salvation really means, or by not rightly dividing the word of truth (see 2 Timothy 2:15) They may be confusing statements made to a different people, for a different time, about a different subject. They may even be using a new Bible version with a corrupt reading.
From the above, we are assured by God Almighty the Saviour that if you believe in the Lord Jesus Christ, you are saved forever. Those that are saved through faith in the Lord Jesus Christ and His shed blood have all their sins paid for by that blood. They have all their sins forgiven by faith in His atoning blood. God will not remember their sins. Therefore, no passage of damnation or condemnation applies to those saved by faith in the Lord Jesus Christ.
Those that have not believed by faith alone are not saved. None of their sins are paid for, forgiven, or forgotten. Every passage of damnation or condemnation applies to them. Many of these quote the very passages that condemn themselves.