A look at why we sin.
The apostle James tells us that we sin when we are tempted to do wrong because of our own lust. Lust is a strong desire for something:
14 But each one is tempted when he is drawn away by his own lust and enticed. 15 Then the lust, when it has conceived, bears sin. The sin, when it is full grown, produces death.
Several verses make it clear that we have a natural tendancy to do wrong:
3 This is an evil in all that is done under the sun, that there is one event to all: yes also, the heart of the sons of men is full of evil, and madness is in their heart while they live, and after that they go to the dead.
9 The heart is deceitful above all things
and it is exceedingly corrupt.
Who can know it?
17 So now it is no more I that do it, but sin which dwells in me. 18 For I know that in me, that is, in my flesh, dwells no good thing. For desire is present with me, but I don’t find it doing that which is good.
The Lord Jesus Christ confirms that our desire to do wrong comes from ourselves:
21 For from within, out of the hearts of men, proceed evil thoughts, adulteries, sexual sins, murders, thefts, 22 covetings, wickedness, deceit, lustful desires, an evil eye, blasphemy, pride, and foolishness. 23 All these evil things come from within, and defile the man.”