The term "sin nature" itself is not used in Scripture, and was invented by Protestant theologians. Nothing wrong with that in itself (we certainly have invented words for concepts that we saw in Scripture but which didn't have a name, starting perhaps with "Trinity").
But what does that term mean, or maybe I should ask "what does that term mean to you?"
I'm not sure that you can draw any general anthropological conclusions from Jesus' condemnation of the Pharisees in Jn 8:44. :-)
Do you think that Adam passed some sort of objective pollution to his descendants -- a pollution that cannot be characterized as a lack of something good and necessary, but as the positive presence of something that shouldn't be there?
Ephesians 2:3 Among whom also we all had our behavior in times past in the lusts of our flesh, fulfilling the desires of the flesh and of the mind; and were by nature the children of wrath, even as others.
Romans 7:14 For we know that the law is spiritual: but I am carnal, sold under sin.
My take on Satan’s role in every man’s nature from Adam to the present is this: When Adam and Eve ate of the Tree, Satan gained rulership over the earth by causing his fall. (God had originally given Adam rulership until iniquity (sin) was found in him. His relationship to man through the ages has been that of a usurper; and until Christ returns, satan will remain the prince of the power of the air and the ruler of this present evil world. Man will again inherit the earth and shall live in it forever when Christ returns and sets up His kingdom. Until that time, ALL of us who have ever been born are subject to satan’s deeds. THAT is the sin nature as I see it. And unless we are saved by the Second Adam, Jesus Christ, we are powerless to free ourselves from that nature.
The term *trinity* itself is not used in Scripture but was invented by Catholic theologians, so should we deny it?
You're going to have to try a much better argument against the sin nature than the one you used.