For God did not send his Son into the world to condemn the world, but in order that the world might be saved through him.
John 3:17 (ESV)
John 3:16 is probably one of the most famous verses in the Bible. But John 3:17 is even more telling--verse 17 lays out God's endgame. God didn't send Jesus into the world in the sense that Jesus arrived on the planet Earth. God sent Jesus into the entire existence that was separated from God.
When we recognize that Jesus was sent into the creation that was out of alignment with God's original, intended design, His purpose begins to take clarity. Notice that Jesus was not sent to condemn this separated existence. (Similar to how Jesus did not condemn the woman caught in adultery, as I previously mentioned.) Jesus's goal was that the entire existence that was separated from God would be restored to its original, intended design.
This means everything Jesus did pivoted around this single purpose of restoration. When we understand why Jesus did what He did (His motives), we can begin to focus on how Jesus did what He did (His actions). This is important because how Jesus did things is often spectacular and sometimes eccentric. But there is at least one consistent observation we can make about Jesus's behaviour: He was gracious and merciful... Except when He wasn't.
From that time Jesus began to show his disciples that he must go to Jerusalem and suffer many things from the elders and chief priests and scribes, and be killed, and on the third day be raised. And Peter took him aside and began to rebuke him, saying, "Far be it from you, Lord! This shall never happen to you." But he turned and said to Peter, "Get behind me, Satan! You are a hindrance to me. For you are not setting your mind on the things of God, but on the things of man."
Matthew 16:21-23 (ESV)
When they had finished breakfast, Jesus said to Simon Peter, "Simon, son of John, do you love me more than these?" He said to him, "Yes, Lord; you know that I love you." He said to him, "Feed my lambs." He said to him a second time, "Simon, son of John, do you love me?" He said to him, "Yes, Lord; you know that I love you." He said to him, "Tend my sheep." He said to him the third time, "Simon, son of John, do you love me?" Peter was grieved because he said to him the third time, "Do you love me?" and he said to him, "Lord, you know everything; you know that I love you." Jesus said to him, "Feed my sheep.
John 21:15-17 (ESV)
These verses contrast two, separate conversations Jesus had with the apostle Peter. The passage in John shows Jesus's grace. What's not immediately evident in English translations is why Jesus asked Peter so many times, "Do you love me?" In the original language Jesus used a word for love that the Bible uses to describe God's love toward His creation. Peter, on the other hand, replied that he considered Jesus a friend. Keep in mind this conversation took place after Jesus was crucified and resurrected. In other words, there really shouldn't have been any doubt in Peter's mind who Jesus was and why He was there.
Compare this with the former verses in Matthew 16, which took place before Jesus was crucified. Peter was sharply correctly; Jesus showed virtually no sympathy for Peter's behaviour. Why?
Everything Jesus did pivoted around the single purpose of restoration.
When Jesus was reminding Peter (in John 21) that he was called by God for a specific function, He needed Peter to recognize that despite his shortcomings and abandonment of Jesus, he was still called and God still loved him. Peter's trepidation to immediately commit wasn't a hindrance to God's plan. But when Peter tried to stop Jesus from being crucified in Matthew 16, he was effectively saying that he was against the single purpose for which Jesus came.
That is the dividing line in Jesus's behaviour; it's consistent throughout His ministry. People who stood opposed to the movement of God or who hindered others from becoming a part of it were rebuked by Jesus. The rest were shown grace and mercy. This dissimilarity can be seen throughout the gospels where Jesus admonishes in Matthew 19:16-22 and John 3:1-21, versus rebukes in Matthew 12:22-32 and Mark 11:15-17.
As disciples of Christ our behaviour must be representative of Jesus, which means our motives and actions ought to be a reflection of His. Regardless of a person's unique function in God's plan, everyone shares the same purpose: to facilitate the restoration of creation to God's original, intended design. This is often condensed into colloquial phrases such as, "Know God and make Him known," or (more scripturally as), "Go into all the world and preach the gospel to every creature." (Mark 16:15 NKJV) The key is that the execution of this plan needs to be consistent with the manner in which Jesus executed it.
Jesus focused on drawing people into a relationship with God. He didn't compromise His position on sin--several times He very clearly directed people to leave their old way of life--but He didn't create barriers between God and a person; our motives and actions need to align with His. This focus to draw people into a relationship with God is the one thing that every follower of Christ has in common.