David numbered the children of Israel in 1st Chronicles 21:1. Because David sinned in doing so, God sent judgement upon the nation of Israel. Why did God bring judgement because of this act?
Here are the comments that my Life Application Study bible shares concerning this verse.
The bible text says Satan provoked David to make a census. Can Satan force people to do wrong? No. Satan only tempted DAvid with the idea, but David decided to act on the temptation. Ever since the Garden of Eden, Satan hs been tempting people to sin. David's census was not against God's Law, but his motive for the census was wrong--pride in his mighty army while forgetting that his real strength came from God. Even Joab, not known for his high moral ideals, recognized the census as sin. From DAvid's example we learn that an action that may not be wrong in itself can be sinful if it is motivated by greed, arrogance, or selfishness. Of our motives, not the action itself, contain the sin. We must constantly weigh our motives before we act.
Hum, Satan can't cause us to sin, he can only tempt us.