5 “O righteous Father,” He says, “the world has not known You.” Just because You are righteous it has not known You. It is as that world which has been predestined to condemnation really deserved, that it has not known Him; while the world which He has reconciled unto Himself through Christ has known Him not of merit, but by grace. For what else is the knowing of Him, but eternal life which, while He undoubtedly withheld it from the condemned world, He bestowed on the reconciled.
On that very account, therefore, the world has not known You, because You are righteous, and hast rendered unto it according to its deserts, that it should not know You: while on the same account the reconciled world has known You, because You are merciful, and, not for any merit of its own, but by grace, hast supplied it with the needed help to know You. And then there follows, “But I have known You.” He is the Fountain of grace, who is by nature God, and, by grace ineffable, man also of the Holy Spirit and the Virgin: and then on His own behalf, because the grace of God is through Jesus Christ our Lord, He adds, “And these have known that You have sent me.” Such is the reconciled world. But it is because You have sent me that they have known: by grace, therefore, have they known.
Source: Tractates on the Gospel of John (New Advent)