The Bible teaches Christians in the Church Age have eternal security through faith in Christ Jesus. What this means is that once a Christian is truly saved, they are saved forever and nothing can demerit or take away your salvation.Of course, as always, when studying the Bible we must dispensationalize! There are many Bible verses that teach you can lose your salvation but all these verses pertain to a different dispensation. Such as Jews under the Old Testament Mosaic law (Ezekiel 18) or Tribulation Saints (which further proves a pre-trib rapture, because of a different salvation method).Now, let's get into the Bible to prove eternal security.Whenever someone does not believe in Eternal Security, it is first of all because of pride and distrust in the Lord Jesus Christ's finished work on the cross. Anyone that believes they can lose their salvation cannot say they are saved by grace through faith alone because they believe they must do good works to remain saved. You will notice heretical pastors that teach you will lose your salvation very often also preach a post-tribulation rapture. The greatest way to teach this doctrine is to teach Christians must go through the tribulation. This will open up the gate to many verses which can be used to show a Christian can lose their salvation. (Parable of the ten virgins, Rev. 14:9-12, etc). Nowhere does the Bible teach Church Age Saints can lose their salvation. Jesus' ministry was primarily directed towards the jews. However, we will still find him bringing in Church Age Christian doctrine on a few occasions such as in John Chapter 10
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.
Paul's ministry, however, was primarily directed towards Christians. Which is why we can get a great deal of Christian doctrine in the books from Romans to Philemon (Hebrews is primarily towards the Jews, hence the name Hebrews)We must remember, things that are different are not the same. If the Bible teaches in one place salvation can be lost, and in another place, it teaches elsewise. Then we have a problem. However, bible believing dispensationalists know to divide the scriptures according to 2 Timothy 2:15. This will solve any contradictions in your Bible and give you a vastly greater understanding of God's word without falling into heresy. Paul taught that a Christian CANNOT lose their salvation
And grieve not the holy Spirit of God, whereby ye are sealed unto the day of redemption.
The Bible shows the Holy Spirit keeps us from losing our salvation "unto the day of redemption". If we could lose our salvation, then it would say "unto the day of apostasy" or likewise. Jesus taught that the Holy Spirit would do great things for us and it would be to our benefit.
Nevertheless I tell you the truth; It is expedient for you that I go away: for if I go not away, the Comforter will not come unto you; but if I depart, I will send him unto you.
So, now we learn that it is the Holy Spirit that keeps us from losing our salvation! This is why Jesus calls him "the Comforter" because we can have comfort and assurance of our salvation. This also explains why Old Testament Saints were able to lose their salvation (Ezekiel 18, etc) But, Church Age Saints can't. Isn't it amazing how scripture with scripture reveals so much about God's word? This also explains why Tribulation Saints can lose their salvation because the Holy Spirit is gone during the tribulation "he who now letteth will let, until he be taken out of the way".
The book of Romans completely destroys any argument with this topic
But to him that worketh not, but believeth on him that justifieth the ungodly, his faith is counted for righteousness.
"to him that worketh not", Did you get that? It doesn't say he works a little bit, or somewhat. It says this man "worketh not", and yet he is saved through his faith in Jesus Christ!
And Romans 4:8
Blessed is the man to whom the Lord will not impute sin.
If we can lose our salvation, then God imputes sin on us. Which means God lied in this verse. Don't you dare make God a liar!
One of the greatest examples of Eternal Security is taught at Romans 8:38-39
38 For I am persuaded, that neither death, nor life, nor angels, nor principalities, nor powers, nor things present, nor things to come,
39 Nor height, nor depth, nor any other creature, shall be able to separate us from the love of God, which is in Christ Jesus our Lord.
We can therefore conclude that Eternal Security is biblically true for the Church Age Saint and if anyone says elsewise let him be accursed.
May the grace of God be with you and help you to understand the scriptures. Amen.