Simon was Jesus' rock and pillar of the church. He was the first follower of Jesus and part of his inner circle. Simon followed Jesus till death. On his way he performed a number of great acts. He healed a lame beggar, he preached on the day of the Pentecost and amassed 3,000 more followers of Christianity.
After Jesus died Simon went on to preach almost all over the world. Without him Christianity wouldn't be what it is today at all. He did have his downs though. On the day of Jesus' death he denied that he knew him three times. Jesus even called it out that he would deny him thrice and the third time he denied him that the rooster would crow, signifying his death.