'Hearts' in the Bible

So keep in mind where you were at first, and be changed in heart and do the first works; or I will come to you, and will take away your light from its place, if your hearts are not changed.

And I will kill her children with death; and all the churches shall know that I am he which searcheth the reins and hearts: and I will give unto every one of you according to your works.

For God hath put in their hearts to fulfil his will, and to agree, and give their kingdom unto the beast, until the words of God shall be fulfilled.