The question of losing one's salvation is one that is a matter of great controversy within the household of Christian faith. There are many Christians who live in mortal fear every day of losing what they have found in Christ because the Bible gives serious warnings about falling away, and Paul himself says that he has to be very careful lest he himself become a castaway. There are biblical warnings about what would happen if we turn our backs on Christ after we've come to a knowledge of him.
On the other hand, there are also many Christians who believe that we will, in fact, never fall away, and I'm numbered among that group. I'm persuaded from a study of Scripture that we can have an assurance of our salvation not only for today but for all time. But the assurance that we have, or confidence in our future estate in salvation, must be based upon the right foundations. In other words, if my confidence that I will persevere is based on my confidence that I will not sin, it's on very shaky ground. One thing the Bible makes clear to me is that even though I am a redeemed person, I will in all likelihood, and inevitably, continue to sin to some degree. If it were up to my strength to persevere to guarantee my future salvation, then I would have very little hope of persevering.
But I'm convinced that the Bible teaches that what God begins in our life, he finishes. Paul teaches, for example, in Philippians, "He who has begun a good work in you will perfect it to the end." My confidence rests in the fact that Jesus promises to intercede for me daily as my Great High Priest. My confidence for my future salvation rests in my confidence that God will keep his promise and that Christ will intercede for me and preserve me. Again, if it were left to me, I would obviously fall away. I like to look at it this way: I'm walking the Christian life with my hand in God's hand. If my perseverance depended upon my holding tightly to God's hand, I would surely fall away because at some point I would let go. But I believe that the Scriptures teach us that God is holding my hand, and because he is holding my hand, I don't have to fear that I will fall ultimately and finally.
Now that doesn't mean that Christians don't involve themselves in serious sins and what we would call in theology "serious and radical fall," but the issue we're discussing here is whether a Christian will ever fall totally and finally. In the New Testament John tells us, for example, that "those who went out from us were never really with us," and that "Christ does not lose those whom the Father has given to him." So my confidence again rests in the intercession of Christ and God's ability and promise to hold on to me. In and of myself I am capable of sinning even unto the loss of my salvation, but I'm persuaded that God in his grace will keep me from that.
"Is it possible for a Christian to lose his salvation because of sins he commits?" and other questions can be found in our Questions Answered section. You can also download the free ebook Can I Lose My Salvation? by R.C. Sproul.