Just to review 1 John 2:27 seems to be telling the reader that they have no need to be taught anything in a book that is teaching them things and in a Testament that is chock full of teaching. What gives?
here and here. Context helps us here. It is a surety that if you take one sentence out of anybody’s speech or letter and try to understand it apart from its context you will have significant problems understanding what that sentence means. The Bible is no different. Each passage, each word is written in the context of an argument or thought that the author is conveying to his audience. 1 John 2:27 is no exception.
Look at the immediate context 1 John 2:18 – 29. John is warning his readers that the antichrist is coming and there are in fact many antichrists out and about. These people are teaching a Christ that is not physical but only a spiritual being (we get this from chapter 1) and is not from the Father. It is in this context about this topic that John says what he says in 1 John 2:27. His readers do not need to be taught about who Christ is, they already know.
Most of the apparent contradictions to which people refer can be resolved by reading a few verses on either side of the text in question. 1 John 2:27 is no exception.