The God whom he had honored deservedly honored him in Return
Such are the proofs by which the Supreme God has made it manifest to us, in the person of Constantine, who alone of all sovereigns had openly professed the Christian faith, how great a difference he perceives between those whose privilege it is to worship him and his Christ, and those who have chosen the contrary part, who provoked his enmity by daring to assail his Church, and whose calamitous end, in every instance, afforded tokens of his displeasure, as manifestly as the death of Constantine conveyed to all men an evident assurance of his Divine love.
Source: Life of Constantine (New Advent)