Theology of islam

From my understanding muslims believe that jesus was not crucified and that someone was made to look like him. Has there been an solidarity on this look alike? This story in the Quran seems to be a given explanation as to why christanity arose, but christans don't follow jesus because he died but because they think he rose from the dead. Is the assumption I'm supposed to take is that after the jesus replacement was killed then allah granted mercy and had the replacement rise from the dead and the double just played along?

Or that jesus just showed up a couple more times after the resurrection and didn't clarify? Or does islam just not answer this question? Better yet why go through this level of trickery at all?