So, as a genuinely converted believer, the last thing that you would want to do is to go back into a willful sinful life, habitually and deliberately practice the works of the flesh as listed in Galatians 5. I maintain that this the passion of every truly converted believer. I think that many underestimate the total and powerful transformation that conversion does within the heart of a person.
I continue to maintain that by appearance there is very little difference between a genuinely converted believer and a religious hypocrite. Their outward religious observance are exactly the same. They both attend church regularly, rise to leadership positions, work tireless to get new members for their church, live very moral lives, know the Bible from end to end, and can talk Christian talk with the best of them. The difference lies in their hearts, which only God can see.
The parable of the prodigal son is a story to emphasise that no matter how reprehensible a person's sinfulness is, when they return and repent, the Father's arms are open wide to receive them. It is very risky to form a doctrine of true believers walking away from Christ and then being restored from a parable spoken by Jesus to unconverted Jews.
I say again, genuine conversion is a total transformation of the heart, worked by the mighty power of the Holy Spirit within a person who sincerely and honestly comes through the narrow gate of full and exclusive confidence in the death and resurrection of Christ to save them.
To say that a person can just choose to follow Christ, and then walk away if he feels like it, is a gross misunderstanding of what conversion to Christ actually is, and is a grievous insult to the Holy Spirit who causes it to happen.