I believe the Bible teaches that you can't "lose" your salvation for one simple reason. It is God who saves us when we put our trust in Him by faith alone in Christ alone. There’s nothing we can do to earn our salvation (Eph.2:8-9). Because God is the one who saves, our salvation cannot be undone. Romans 8:38-39 speaks to this very clearly.

Perhaps the strongest passage about our security in Christ is John 6:35-37, where Jesus says, “However, those the Father has given me will come to me, and I will never reject them.”