Think about it this way. How many children can a Christian molest and not face condemnation?
Can a Christian just molest a child on the odd occasion, just so long as they don't make a practiced habit of it?
If we are honest we know the answer to that question. Child molestation is out of the question for any Christian.
If one thinks that they can occasionally molest a child, you know, just a couple of times a year, so long as they don't do it all the time, so long as the "Holy Spirit wins out" then what sort of doctrine is that? It is the opposite of the heart purity Jesus taught.
A pure heart will NEVER molest a child. Not once.
Why is it different for any other sin?
Willful sin is out of the question for a Christian. The new birth involves a washing, a real cleansing from sin. The new birth is not a temporal bath which we are to keep going back to. That attitude is an utter mockery of Jesus Christ which is why we have this warning...
Heb 10:22 Let us draw near with a true heart in full assurance of faith, having our hearts sprinkled from an evil conscience, and our bodies washed with pure water.
Heb 10:23 Let us hold fast the profession of our faith without wavering; (for he is faithful that promised
Heb 10:24 And let us consider one another to provoke unto love and to good works:
Heb 10:25 Not forsaking the assembling of ourselves together, as the manner of some is; but exhorting one another: and so much the more, as ye see the day approaching.
Heb 10:26 For if we sin wilfully after that we have received the knowledge of the truth, there remaineth no more sacrifice for sins,
Heb 10:27 But a certain fearful looking for of judgment and fiery indignation, which shall devour the adversaries.
Heb 10:28 He that despised Moses' law died without mercy under two or three witnesses:
Heb 10:29 Of how much sorer punishment, suppose ye, shall he be thought worthy, who hath trodden under foot the Son of God, and hath counted the blood of the covenant, wherewith he was sanctified, an unholy thing, and hath done despite unto the Spirit of grace?
To approach God seeking forgiveness of sins and then to go out and recommit that which God forgave one for is to hold the forgiveness of God in contempt. There is no forgiveness for one who holds God in contempt. None.
Anyone who holds God in contempt has to come clean with God once and for all and forsake their rebellion otherwise there is no hope. Sure one can comfort themselves with religion but one day every single person is going to stand before God NAKED without their religion. Our HEARTS WILL BE MANIFEST and if our hearts are not clean we will be condemned. Trusting in some cloak for filthiness is self deception, the filthiness has to be destroyed and replaced with purity. That is what Jesus taught. Jesus explicitly warned the religious people of His day to cleanse their hearts. He didn't preach a sin cloak or that God looks the other way. Jesus told them to repent, turn from their evil and obey God. It is that simple. Do that and live. Do it not and die.