Because it is God who said, “Out of darkness Light shall shine,” the One who shone in our hearts to give the illumination of the knowledge of the glory of God in the face of Jesus Christ. Isa. 42:6, 7, 16
And Jehovah your God will circumcise your heart, and the heart of your seed, to love Jehovah your God with all your heart, and with all your soul, that you may live.
Having purified your souls in the obedience of the truth through the Spirit to unpretended brotherly love, love one another fervently out of a pure heart,
Brothers, I do not write a new commandment to you, but an old commandment which you had from the beginning. The old commandment is the Word which you heard from the beginning.
Everyone having been regenerated of God does not sin, because His seed abides in him, and he is not able to sin, because he has been generated from God.
If anyone says, I love God, and hates his brother, he is a liar. For the one not loving his brother whom he has seen, how is he able to love God whom he has not seen?
Every one believing that Jesus is the Christ has been generated from God. And everyone loving the One generating also loves the one having been generated of Him.