"If anyone sees his brother sinning, if the sin is not deadly, he should pray to God and he will give him life. This is only for those whose sin is not deadly. There is such a thing as deadly sin, about which I do not say that you should pray. All wrongdoing is sin, but there is sin that is not deadly." (1 John 5:16-17)
"This is only for those whose sin is not deadly"
If there is a sin that is not deadly, there must be a sin that is deadly.
So there are differing levels of sin...or was John a liar?