God did not shine our hearts for us to keep the light hidden, but for us to give light to those whom the god of this world blinded their minds due to their unbelief; therefore the light of the glorious gospel is hid from them. This is why we are called the light of the world, as speaking spirits (made in His image and likeness) so that we can operate in the same manner God does by allowing the knowledge of our Lord Jesus Christ shine forth through our hearts and enlighten the hearts of those that are lost.