God is one and there is no other. Therefore, we must give to God, what is God's.
In the Gospel of Matthew, Jesus says to return to Ceaser what is Ceaser's, and to God what is God's. The Denarius had Ceaser's image, hence it had to be returned to Ceaser. However, as humans, we are imprinted in the image of God. Hence, we must give ourselves to God by working out God's plans and mission in this world.