Did you think that a person who had become a Christian could not go back to living in the flesh? When you read Rom 7, do you think that Paul does not describe himself here? Why do you think Paul says “I pummel my body, and subdue it”?
So then they that are in the flesh cannot please God.
But ye are not in the flesh, but in the Spirit, if so be that the Spirit of God dwell in you. Now if any man have not the Spirit of Christ, he is none of his.
And if Christ be in you, the body is dead because of sin; but the Spirit is life because of righteousness.
But if the Spirit of him that raised up Jesus from the dead dwell in you, he that raised up Christ from the dead shall also quicken your mortal bodies by his Spirit that dwelleth in you.
Therefore, brethren, we are debtors, not to the flesh, to live after the flesh.
For if ye live after the flesh, ye shall die: but if ye through the Spirit do mortify the deeds of the body, ye shall live.
For as many as are led by the Spirit of God, they are the sons of God.
My little children, these things write I unto you, that ye sin not. And if any man sin, we have an advocate with the Father, Jesus Christ the righteous:
And he is the propitiation for our sins: and not for ours only, but also for the sins of the whole world.
And hereby we do know that we know him, if we keep his commandments.
He that saith, I know him, and keepeth not his commandments, is a liar, and the truth is not in him.
But whoso keepeth his word, in him verily is the love of God perfected: hereby know we that we are in him.
Behold, what manner of love the Father hath bestowed upon us, that we should be called the sons of God: therefore the world knoweth us not, because it knew him not.
Beloved, now are we the sons of God, and it doth not yet appear what we shall be: but we know that, when he shall appear, we shall be like him; for we shall see him as he is.
And every man that hath this hope in him purifieth himself, even as he is pure.
Whosoever committeth sin transgresseth also the law: for sin is the transgression of the law.
And ye know that he was manifested to take away our sins; and in him is no sin.
Whosoever abideth in him sinneth not: whosoever sinneth hath not seen him, neither known him.
Little children, let no man deceive you: he that doeth righteousness is righteous, even as he is righteous.
He that committeth sin is of the devil; for the devil sinneth from the beginning. For this purpose the Son of God was manifested, that he might destroy the works of the devil.
Whosoever is born of God doth not commit sin; for his seed remaineth in him: and he cannot sin, because he is born of God.
In this the children of God are manifest, and the children of the devil: whosoever doeth not righteousness is not of God, neither he that loveth not his brother.
Please stop blaming the Church for your own failings.