A new heart also will I give you, and a new spirit will I put within you: and I will take away the stony heart out of your flesh, and I will give you an heart of flesh.
A new heart - a new mind and will.
And a new spirit will I put within you - i:e., a new motive and principle of action.
I will take away the stony heart out of your flesh - the heart unimpressible in serious things; like the "stony ground" (Matthew 13:20), unfit for receiving the good seed so as to bring forth fruit.
And I will give you an heart of flesh - not 'carnal,' in opposition to 'spiritual;' but impressible and docile, fit for receiving the good seed. In Ezekiel 18:31 they are commanded, "Make you a new heart and a new spirit." Here God says, "A new heart will I give you, and a new spirit will I put within you." Thus the responsibility of man and the sovereign grace of God are shown to be co-existent. Man cannot make himself a new heart unless God gives it (Philippians 2:12-13).