I Chronicles 21:1 And Satan stood up against Israel, and provoked David to number Israel.
I think it is easy for us to ignore Satan but we do so at our peril. He is real. He has real power. He influenced David and caused Israel and David to suffer. Satan provoked David. He motivated him. He gave him the idea. He caused David to at least think about numbering or counting Israel. David thought he thought of it but the thought came from Satan.
Just like when Peter was just trying to love Jesus and keep Him from going to the cross. Peter thought he said it but Jesus recognized it as coming from Satan.
Satan wanted to harm Israel. He knew that he could do that through messing with David. David thought he was just considering what he wanted when he was playing into the hands of Satan and sin.
Be careful and consider each of your thoughts. Try the spirits and make sure your thoughts come from the Lord and not Satan or you will suffer from it.