I can understand your thoughts regarding this subject. I was raised believing a Christian's perseverance is dependent on his resolve to press on in Christ. While this resolve should never be looked over, I have been persuaded by the Scriptures that the perseverance of a Christian is dependent on God's faithfulness. Before I move on to the Scriptures regarding this, I want to say that I recognize this is something you will have to pray about and come to a decision on yourself. I don't want to move you over to one camp or another because of what I say. God is the one who should convince us of His Word! With that being said, I would like to show you why I believe in eternal security.
Jeremiah 32:39”“41 (ESV)
39 I will give them one heart and one way, that they may fear me forever, for their own good and the good of their children after them. 40 I will make with them an everlasting covenant, that I will not turn away from doing good to them. And I will put the fear of me in their hearts, that they may not turn from me. 41 I will rejoice in doing them good, and I will plant them in this land in faithfulness, with all my heart and all my soul.
This Scripture explains God's faithfulness in the New Covenant. God says He will not turn away from doing good to His children and that the fear of God He will place in their hearts will keep them from going astray.
Hebrews 8:8”“12 (ESV)
8 For he finds fault with them when he says: "Behold, the days are coming, declares the Lord, when I will establish a new covenant with the house of Israel and with the house of Judah, 9 not like the covenant that I made with their fathers on the day when I took them by the hand to bring them out of the land of Egypt. For they did not continue in my covenant, and so I showed no concern for them, declares the Lord. 10 For this is the covenant that I will make with the house of Israel after those days, declares the Lord: I will put my laws into their minds, and write them on their hearts, and I will be their God, and they shall be my people. 11 And they shall not teach, each one his neighbor and each one his brother, saying, ‘Know the Lord,’ for they shall all know me, from the least of them to the greatest. 12 For I will be merciful toward their iniquities, and I will remember their sins no more.”
In this Scripture, it explains why the Old Covenant was not sufficient, or at least one reason why. That reason is the fact the Old Covenant did not ensure the continual obedience of the ones the Lord made a covenant with. Verse 9 shows this. With the New Covenant the laws are not be external but internal, literally in "their minds" and "their hearts." This will ensure obedience, and all of God's people will know the Lord.
John 14:19 (ESV)
19 Yet a little while and the world will see me no more, but you will see me. Because I live, you also will live.
Jesus is the reason why we will live, and because He will never die again we will never die. The next several verses from Romans expounds on this.
Romans 6:1”“11 (ESV)
6 What shall we say then? Are we to continue in sin that grace may abound? 2 By no means! How can we who died to sin still live in it? 3 Do you not know that all of us who have been baptized into Christ Jesus were baptized into his death? 4 We were buried therefore with him by baptism into death, in order that, just as Christ was raised from the dead by the glory of the Father, we too might walk in newness of life.
5 For if we have been united with him in a death like his, we shall certainly be united with him in a resurrection like his. 6 We know that our old self was crucified with him in order that the body of sin might be brought to nothing, so that we would no longer be enslaved to sin. 7 For one who has died has been set free from sin. 8 Now if we have died with Christ, we believe that we will also live with him. 9 We know that Christ, being raised from the dead, will never die again; death no longer has dominion over him. 10 For the death he died he died to sin, once for all, but the life he lives he lives to God. 11 So you also must consider yourselves dead to sin and alive to God in Christ Jesus.
This clearly explains who a Christian is. Each Christian once was a slave to sin. Consider yourself before being saved. Could you live the redeemed life by your own strength? I know I could not, even though I tried very hard to do so. No matter what I did I kept going back to the sin I hated and loved at the same time. But now, as verse 7 says, I have been set free from sin! Verse 5 gives one of the best arguments for eternal security in my opinion. He says we shall certainly partake in the resurrection if we have been united with Christ in His death.
Romans 6:14 (ESV)\t
14 For sin will have no dominion over you, since you are not under law but under grace.
Just as the ESV Study Bible commentary says, this is not a command but a promise.
Romans 6:22”“23 (ESV)
22 But now that you have been set free from sin and have become slaves of God, the fruit you get leads to sanctification and its end, eternal life. 23 For the wages of sin is death, but the free gift of God is eternal life in Christ Jesus our Lord.
Again, we have been set free from sin. Coupled with the promise of Romans 6:14, how can we fall back into sin and be lost?
Romans 8:28 (ESV)
28 And we know that for those who love God all things work together for good, for those who are called according to his purpose.
How can all things work together for our good if we fall away and are lost forever? The emphasis is on the word "all." God is at work in us to ensure all things work together for our good. This is not of us, but a work of God. If it were of us, it could not be said that all things work together for our good because we would surely fall away apart from God's amazing grace.
1 John 3:6”“10 (ESV)
6 No one who abides in him keeps on sinning; no one who keeps on sinning has either seen him or known him. 7 Little children, let no one deceive you. Whoever practices righteousness is righteous, as he is righteous. 8 Whoever makes a practice of sinning is of the devil, for the devil has been sinning from the beginning. The reason the Son of God appeared was to destroy the works of the devil. 9 No one born of God makes a practice of sinning, for God’s seed abides in him, and he cannot keep on sinning because he has been born of God. 10 By this it is evident who are the children of God, and who are the children of the devil: whoever does not practice righteousness is not of God, nor is the one who does not love his brother.
This is my last verse to give. Habitual sin cannot be a part of a Christian. It is alien to the Christian. The pattern of a Christian's life reveals a lifestyle that is striving to be like Christ. There are ups and downs, but the Christian will prevail because he has been born of God. Christ's Spirit is in him, and he cannot live a life of habitual sin because of Christ in him. Much attention should be given to verse 9. God's seed (Christ; see Gal. 3:16. The word "offspring" means "seed") remains in the Christian and keeps him from sinning. The fact he has been born of God is another reason why he cannot keep on sinning. Therefore, this prevention of the Christian from entering into a life of sin, and that prevention being from God, is a serious indicator that the true Christian cannot fall away. This is due to the faithfulness of God.
We must fear God and never live in a state of false confidence that sin can never touch us. That is foolishness. A Christian can sin and can sin very severely as well. But God's faithfulness will ensure the Christian is never lost and that the Christian repents of his sin. I do not believe in "easy believism" or "hyper grace." Both are totally contrary to the Bible. A true Christian will love God and hate sin. He will weep if he sins and yearn for God when he has begun to stray. To bring this to a close, God's Word, from what I showed you, has very much to say on this subject, and I believe it shows that eternal security is a biblical teaching.