Why must every prophecy in Scripture be fulfilled, even those still in the future?
Every prophetic word must be fulfilled because God’s truthfulness is at stake; if one prophecy failed, God would be a liar. The text therefore declares that all prophecy, including what is still future, must come to pass exactly, down to the last jot and tittle, and it will.
Les teaches from Acts 3 that Peter, addressing the brethren, acknowledged they had crucified Christ in ignorance, as did also their rulers. But Peter points to the other side: those things God had before showed by the mouth of all His prophets—that Christ should suffer—He has fulfilled. Les stresses that anytime something is written in prophecy, it has to be fulfilled to the last jot and tittle, or it would make God a liar. Everything written prophetically has to come to pass; everything still future has to happen and it will, otherwise God would be a liar. Peter thus says Christ had to die because prophecy had foretold it. Immediately after, Peter calls them to repent and be converted, the same format as Acts 2:38—turn your direction, change your thinking.