1 Chronicles 21     Now Satan stood up against Israel, and moved David to number Israel.

² So David said to Joab and to the leaders of the people, “Go, number Israel from Beersheba to Dan, and bring the number of them to me that I may know it.”

2 Samuel 24:1    Again the anger of the Lord was aroused against Israel, and He moved David against them to say, “Go, number Israel and Judah.”

I picture God with a big umbrella over Him, under which we can shelter and be protected from harm and danger, if we are close to Him. But if you move away from Him, as Israel did at the time you are talking about, you move out of God’s protection, and are an easy prey for the devil. God allows every one of us the power of free choice, and will never go against our decisions, even though it brings us into mortal danger. He never forces, only draws us with His love.

At this point, the whole nation of Israel, had once again sinned and walked away from God. And when God is not at the central point of our lives, the devil has free access. God is not even thought of by David and his nation, and he therefore is open to the suggestion of the devil to take a census of the nation. Numbering your fighting men, which the census was all about, signified to God that He was no longer the One in whom they trusted, and they wanted to know the strength of their army. 1 Chronicles 21 states the position more accurately, that Satan was the one who started the ball rolling. The other verse says that it was God who suggested the census, but what it is really saying is that God allowed the devil to suggest it to David, because God could not act when the nation had walked away from Him. The reason why it could not be God suggesting it to David, is given below.

James 1:13   Let no one say when he is tempted, “I am tempted by God”; for God cannot be tempted by evil, nor does He Himself tempt anyone.

God will never cause anyone to sin, only allow the devil to do it, if the person has turned away from God’s protection. I believe that Young’s Literal Translation of 2 Samuel 24:1    gives it correctly:

“And the anger of Jehovah addeth to burn against Israel, and [an adversary] moveth David about them, saying, `Go, number Israel and Judah.’”

I hope that this makes sense to you. God bless!