I have often struggled with this topic - one side says if you continue to struggle in or are in bondage to a sin you might never had been saved. The other other side says you could loose your salvation.. Sanctification is a process. Even Paul in Romans 7 appeared to struggle. Then in Romans 8 offered the solution of walking in the Spirit which is something we learn to do by greater dependence on the Holy Spirit rather than our own resources One might wonder if one is saved if they struggle greatly with some sins of Galatians 5:19-21 and are slow to develop the fruit of Galatians 5:22-23. I have often thought our Salvation is secure if we abide in him according to John 15:4 Did the prodigal son abide? No he rejected his father and abused his inheritance in great sin. He repented and return to his father who forgive him, put a ring on his finger and restored the relationship but if he had stayed in the pig pen would he have been lost?