Early Christians on Isaiah - The Proof From Prophecy Approach?

i'm curious about how you wrestle with that approach to reading texts a messianically in the book of isaiah. So theyare kind of mining back through the text am in trying to find these different proof texts which support their cases. But on the other hand, when you read isaiah seven 14 and its context, its clearly talking about a young child who can be born in the eighth century. And so i think that even points where i wasn't so much agreeing with some of the moves they were making exactly, i think i grew to appreciate kind of why they were doing that.