In Matthew chapter 16, we will focus in on verses 20-28. We will see more evidence, straight from the mouth of Jesus, that Salvation is through him alone.
From that time on Jesus began to explain to his disciples that he must go to Jerusalem and suffer many things at the hands of the elders, chief priests and teachers of the law, and that he must be killed and on the third day be raised to life.
Peter took him aside and began to rebuke him. “Never, Lord!” he said. “This shall never happen to you!”
Jesus turned and said to Peter, “Get behind me, Satan! You are a stumbling block to me; you do not have in mind the things of God, but the things of men.”
Then Jesus said to his disciples, “If anyone would come after me, he must deny himself and take up his cross and follow me. For whoever wants to save his life will lose it, but whoever loses his life for me will find it. What good will it be for a man if he gains the whole world, yet forfeits his soul? Or what can a man give in exchange for his soul? For the Son of Man is going to come in his Father’s glory with his angels, and then he will reward each person according to what he has done. I tell you the truth, some who are standing here will not taste death before they see the Son of Man coming in his kingdom.”
Notice that Jesus says his punishment suffering and death must happen. If there were any other way to God, then Jesus didn’t have to suffer and die. Peter even argues that Jesus should not die and Jesus says that those thoughts are not of God, but of men and Satan. God knows that the only way to reconcile mankind to Himself is to provide a perfect sacrifice to take the punishment we deserve for choosing our own ways over His. God’s perfect justice demands penalty for sin, but God’s perfect love provides a way for sinful man to escape punishment without ignoring the problem of judgment and justice.
Then Jesus says that those who want to try to save their life on their own, will end up losing their life. But whoever dies to themselves for the sake of Jesus will end up finding life. He points out that even if a man were able to gain the whole world by his own efforts, he would still end up losing his soul. We cannot earn our salvation. It is a gift of God given to those who deny themselves and follow Jesus.