In natural language the word "manifest" simply means to make something clear or obvious. It's interesting, though, that in the Bible the word "manifest" appears only in the New Testament, and -- in the Gospels particularly -- is generally connected with the Lord Himself. To "manifest" something or make something manifest means to reveal the deepest true ideas about the Lord in the Bible, and is something that happens particularly in the process of bringing one church to an end and beginning another. This is, of course, what the Lord was doing during his life in this world; by revealing new and deeper truths, He was bringing an end to the Israelites as the "true" church and launching its successor, the Christian Church.