He does so through prophets and evangelists, but most of all through his eternal and only-begotten Son Jesus Christ, who is his Living Word. God's self-revelation, however, is not delivered in a bundle, like a library file for a research project or a computer download. In this way, God breaks through the confusion of human sin and allows us to know him. What we could not get on our own, God gives us freely. Through divine revelation, God uses our human abilities, assisted by his grace, to give us super-human knowledge.
Revelation is, then, a gift.
Revelation is also complete in Jesus Christ, and this completeness is part of the revelation itself. It is also very possible that we have reached the functional limits of our worldly capacity to know God, as St. Paul tells us. Now we see through a glass darkly, or by reflections in a mirror. It is only later that we shall see face to face. The body of our knowledge of God in this world is complete, but our understanding is not.