Some people say that there are no unambiguous prophecies about Jesus in the OT, hence such verses are open to interpretations. For example, even in one of the strongest prophecy about Jesus, Isaiah 53:10 it says, “Yet it was the Lord’s will to crush him and cause him to suffer, and though the Lord makes his life an offering for sin, he will see HIS OFFSPRING and prolong his days, and the will of the Lord will prosper in his hand.” Looking at this verse, people can think that this person, whom Isaiah 53 describes, would have an offspring, but Jesus didn’t ever have one. How can we have the assurance of the prophecies about Jesus that they talk about Jesus himself?
Unambiguous is in the eyes of the beholder, as they say. In my opinion, Isaiah 53 is rather obviously talking about the historical person we know as Jesus of Nazareth. So many details fit exactly, that I believe a reasonable person would agree that this is rather obvious. He was despised and rejected. Fact. He was silent when accused (53:7). Fact. That is why he was convicted on trumped up charges. He was pierced (53:5), unless we can accuse John of outright lying in his gospel. He was buried in a rich person’s grave, etc..
But, he was not literally “crushed.” (53:10). This crushing is clearly metaphorical. How many people actually, literally, get crushed? Also, he has many “offspring” which is all those who follow him and who he calls friend and brother. This is the obvious interpretation. His offspring are spiritual, not genetic. We are Jesus’ friends (John 15:15). We are his brothers and sisters (Hebrews 2:11). We are his children according to Galatians 3:26. All of these claims are spiritual/symbolic, not literal. This is what Isaiah 53:10 is talking about.
Is there any conceivable ambiguity here? Yes. Is the conclusion that this is a prophecy, and that it was fulfilled in Jesus the most reasonable one? Definitely.
God gives us free will and he does not force us to believe. To those who are unwilling to accept what seems rather obvious to you and me, God gives them sufficient room to find an ambiguity and to not accept the obvious, which is that this is a prophecy which was fulfilled by Jesus.
What about Psalm 22:16? “They have pierced my hands and my feet.” Is this ambiguous? Hmmm…. I guess. It depends what you mean by ambiguous. Who else in David’s time got his hands and feet pierced? Seems pretty unambiguous to me, but I am sure that those who choose not to believe in Christ can dig up some sort of ambiguity there. On judgment day, we will answer to God if we refuse to accept the rather clear implications of the dozens of messianic prophecies in the Bible.