I will try to make this brief but to the point:
Sin is the transgression of Gods law (Ten Commandments)
Sin consist of the lust of the eyes, flesh and the pride of life. 1John 2:16

Jesus said:Or have ye not read in the law, how that on the sabbath days the priests in the temple profane the sabbath, and are blameless? Mat.12:5
They had to work on the sabbath to offer up sacrifices unto God but this was
OK because God told them to do it, but they also were working on the sabbath which was forbidden, yet were blameless.

Paul tells us he didn’t know what lust was except the law had said thou shalt
not covet. Rom. 7:7 (desire of that which belongs to another)

This is the sin that’s not unto death but it is still a sin:
(sex between a married couple)
Psalm 51:5 Behold, I was shapen in iniquity; and in sin did my mother conceive me.
Lust (desire) for our wife and through this relationship we have born a child.
This is the only way we can have children.

Now as we grow in Christ, he tells us flee youthful lust. 2 Tim 2:22
God tells us through Paul how we ought to possess his vessel, Not in the lust of concupiscence and.The. 4:4-9.
Make not provision for the flesh. Rom. 13:13

We need to look at God’s words more closely not that I cannot enjoy my wife,
but hopefully we will be growing more spiritually that we may mortify the deeds of the flesh and walk in the spiritual likeness of Christ not after the hunger of this world but after things that are above. Col. 3:1-6

1 Cort. 2:11-16