In today's Gospel reading from Mark 8, Jesus asked his disciples, "Who do people say that I am?" Peter got it right, for he replied, "You are the Christ." Our duty and goal is precisely to make this truth known to all!
Right after Peter said the right thing, he blundered. Jesus told the disciples that he must suffer greatly and be rejected by the elders, the chief priests, and the scribes, and be killed, and rise after three days. Peter took him aside and began to rebuke him. At this Jesus turned around and, looking at his disciples, rebuked Peter and said, "Get behind me, Satan. You are thinking not as God does, but as human beings do." We are very much like Peter, following our emotion and not discerning the will of God. So, be aware that Satan is always there, prompting us to go against the Lord. And to know God's thoughts, seek to attain union with him.