This is not the plan I would have come up with. Peter has just confessed that Jesus is the Messiah... and then Jesus follows with a plan that involves suffering, death, and resurrection. Had I been in charge, I might have developed a plan that omitted the first two parts of that and focused on glorification.
Thankfully, God is in control. God understood what must be done, even if it doesn't make sense to human minds. God knew, and God was committed to saving humanity and was therefore willing to pay any price. God wasn't afraid of the necessary suffering, because God thinks you and I are worth it.
So let us not shy away from what we do not understand. May we ask big questions and follow God wherever God may lead, trusting in God's plans and God's ways, which are greater than our own.