Doctrine of Sin: Concupiscence
Concupiscence [kon-ku’-pi-sens] (noun): desire for something sinful, often involuntary
Every part of us is corrupted
1 And you were dead in the trespasses and sins 2 in which you once walked, following the course of this world, following the prince of the power of the air, the spirit that is now at work in the sons of disobedience— 3 among whom we all once lived in the passions of our flesh, carrying out the desires of the body and the mind, and were by nature children of wrath, like the rest of mankind. [Ephesians 2:1-3]
2. Our wrong desires are wrong (even if we did not choose them)
17 “You shall not covet your neighbour's house; you shall not covet your neighbour's wife, or his male servant, or his female servant, or his ox, or his donkey, or anything that is your neighbour’s.†[Exodus 20:17; (Matthew 5:21-22, 27-28; Romans 1:22-32)]
Noticing vs desiring?
3. Our temptations may be caused by indwelling sin (and previous sinning)
2 Count it all joy, my brothers, when you meet trials (peirasmois) of various kinds, 3 for you know that the testing of your faith produces steadfastness.
13 Let no one say when he is tempted (peirazomenos), “I am being tempted by Godâ€, for God cannot be tempted with evil, and he himself tempts no one. 14 But each person is tempted when he is lured and enticed by his own desire. 15 Then desire when it has conceived gives birth to sin, and sin when it is fully grown brings forth death. [James 1:2-3, 13-15]
…but resisting those temptations is still crucial
Was Jesus tempted as we are? (Distinguo!)
Yes. 15 For we do not have a high priest who is unable to sympathize with our weaknesses, but one
who in every respect has been tempted as we are, yet without sin. [Hebrews 4:15]
No. Jesus’ temptations were not caused by indwelling sin
3 By sending his own Son in the likeness of sinful flesh and for sin, [God] condemned sin in the flesh…
[Romans 8:3; (Matthew 4:1-11)]
4. Therefore the Christian life is a fight
13 For if you live according to the flesh you will die, but if by the Spirit you put to death the deeds of the body, you will live. [Romans 8:13; (Romans 13:14; Colossians 3:5)]
Our real identity is our new self
20 Now if I do what I do not want, it is no longer I who do it, but sin that dwells within me.
[Romans 7:20; (1 Corinthians 6:11)]
Progress now, perfection later
15 Practise these things, immerse yourself in them, so that all may see your progress. [1 Timothy 4:15]
2 Beloved, we are God's children now, and what we will be has not yet appeared; but we know that
 when he appears we shall be like him, because we shall see him as he is. 3 And everyone who thus
hopes in him purifies himself as he is pure. [1 John 3:2-3]