Your base point, that children of God commit sin, is a moot point.
It is written..."Whosoever abideth in him sinneth not: whosoever sinneth hath not seen him, neither known him." (1 John 3:6)
And..."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." (1 John 3:8-10)
You are implying that grape vines can bear figs.
Here is what Jesus taught about a brother who sins —
“What do you think? If a man has a hundred sheep, and one of them goes astray, does he not leave the ninety-nine and go to the mountains to seek the one that is straying? And if he should find it, assuredly, I say to you, he rejoices more over that sheep than over the ninety-nine that did not go astray. Even so it is not the will of your Father who is in heaven that one of these little ones should perish. “Moreover if your brother sins against you, go and tell him his fault between you and him alone. If he hears you, you have gained your brother. But if he will not hear, take with you one or two more, that by the mouth of two or three witnesses every word may be established.’ And if he refuses to hear them, tell it to the church. But if he refuses even to hear the church, let him be to you like a heathen and a tax collector. Matthew 18:12-17
- Moreover if your brother sins against you, go and tell him his fault between you and him alone. If he hears you, you have gained your brother.
When a Christian commits a sin, then they must repent confess their sin and be forgiven.
How many times can a Christian be forgiven ?
Then Peter came to Him and said, “Lord, how often shall my brother sin against me, and I forgive him? Up to seven times?”
Jesus said to him, “I do not say to you, up to seven times, but up to seventy times seven. Matthew 18:21-22
JLB