God says He will preserve His words forever...He never said that about Ignatius' writings...
God never spelled out what his writings are. That's why there were canon "turf wars." Who decided that Paul's letters would be scripture and Ignatius' would not? Who decided what that the Book of Enoch wold not be inspired when it was read in many churches as if it were and in the Ethiopian Church it is still considered scripture?
The only books God allegedly wrote, are the Five Books of Moses, dictated word-for-word to him, or so the Jews believe. Pretty much the way Muslims believe that Allah did the same thing to illiterate Mohammad (who, get this, memorized every word exactly, and then had a scribe write it down later! You don't believe it? I thought with God everything is possible).
So, if you really want to play it by the rules, then only the Five Books of Moses are the inspired Books. Like I said, a myth on top of a myth does not make it truth.