Heart is defined as the seat of moral life and character. “Heart is: The spring of all our actions and purposes; the seat of moral life and character; the moral affections and character itself; the individual disposition and character; as, a good, tender, loving, bad, hard, or selfish heart.” Webster’s Revised Unabridged Dictionary
Heart is the first place God works His creation of new creatures.
It is with our heart that we believe. “8 But what does it say? “The word is near you, in your mouth and in your heart;”✡ that is, the word of faith which we proclaim: 9 that if you will confess with your mouth that Yeshua is Lord and believe in your heart that God raised him from the dead, you will be saved. 10 For with the heart one believes resulting in righteousness; and with the mouth confession is made resulting in salvation. 11 For the Scripture says, “Whoever believes in him will not be disappointed.”✡ Romans 10:8-11
The moment we believe, God creates us in Christ Jesus. “He has made us what we are, creating us in Christ Jesus to do good works, in which God long ago planned for us to live.” Eph 2:10 AAT
Two of Paul’s prayers for our hearts.
15 For this cause I also, having heard of the faith in the Lord Yeshua which is among you and the love which you have toward all the holy ones, 16 don’t cease to give thanks for you, making mention of you in my prayers, 17 that the God of our Lord Yeshua the Messiah, the Father of glory, may give to you a spirit of wisdom and revelation in the knowledge of him, 18 having the eyes of your hearts† enlightened, that you may know what is the hope of his calling, and what are the riches of the glory of his inheritance in the holy ones, 19 and what is the exceeding greatness of his power toward us who believe, according to that working of the strength of his might 20 which he worked in Messiah when he raised him from the dead and made him to sit at his right hand in the heavenly places, 21 far above all rule, authority, power, dominion, and every name that is named, not only in this age, but also in that which is to come. 22 He put all things in subjection under his feet, and gave him to be head over all things for the assembly, 23 which is his body, the fullness of him who fills all in all. Ephesians 1:15-23
I pray that Christ may make His home in your hearts through your faith; so that having your roots deep and your foundations strong, in love, you may become mighty to grasp the idea, as it is grasped by all God’s people, of the breadth and length, the height and depth—yes, to attain to a knowledge of the knowledge-surpassing love of Christ, so that you may be made complete in accordance with God’s own standard of completeness. Now to Him who, in exercise of His power that is at work within us, is able to do infinitely beyond all our highest prayers or thoughts—to Him be the glory in the Church and in Christ Jesus to all generations, world without end! Amen. Eph 3:9-21 WNT
Unless otherwise noted, all Scripture quoted above is from the World Messianic Bible.