All throughout his First Apology, Justin Martyr points to the fulfillment of prophecy as evidence for the truth of Christianity. In chapter 53, we read that fulfilled prophecies are "sufficient for the persuasion of those who have ears to hear and understand" (ANF 1:180). The Greek term translated as “sufficient” is αὐτάρκεις, a term that denotes something being self-sufficient. For Justin, the fulfillment of prophecies (e.g., Isa 7; 52-53; Psa 2 and 110) is not just evidence but proof of Christianity.
For a good scholarly work on this and other issues raised by Justin in his writings, see David E Nyström, The Apology of Justin Martyr: Literary Strategies and the Defence of Christianity.