[HarleyD]

It asserts that Christians don't sin (although in verse 11 he urges them not to sin!).

I don't know of any Protestants who would assert that Christians do not sin.

[Cvengr]

I concur, although there is no temptation too great than that which may be resisted.

[kosta50]

I don't know of any Protestants who would assert that Christians do not sin

No, you asserted that those who deliberately live in sin are not Christians.

Which goes back to my question: what makes them sin, their own choice, or God? If it's their choice, HD, they they deliberately, knowingly and willingly commit sin every day, every hour...constantly, repetitively over and over again.

I would call constant sinning the same as "living in sin" without trying to split hairs. The only question is if the Protestants who you say sin do so by their own will or by God's.

If it's by their own will, then they deliberately live in sin. The only other alternative is God and that seems not a very good alternative in this case.