(This is not a duplicate of [halacha - Why was King David Punished for Sending Others to Conduct a Census? - Mi Yodeya](https://judaism.stackexchange.com/questions/55395/why-was-king-david-punished-for-sending-others-to-conduct-a-census).)

[1 Chronicles 21](http://mechon-mamre.org/p/pt/pt25a21.htm), and [2 Samuel 24](http://mechon-mamre.org/p/pt/pt08b24.htm) relate how King David took it upon himself to number the people of Israel.

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> .י הָאֱלֹהִים, עַל-הַדָּבָר הַזֶּה; וַיַּךְ, אֶת-יִשְׂרָאֵל. 
> 
> 
> And God was displeased with this thing; therefore He smote Israel.
> 
> 
> 

This was obviously not a good thing, but why?

Taking a census can be a preparation for war and/or taxation.
I've heard that David's sin was in this demonstration that Israel wasn't relying on the Lord for peace and prosperity, but I heard the explanation from a Christian source.

Is that an appropriate interpretation?