The need to take on Jesus Christ as your personal savior by water baptism.
Baptism brings the repentant people out of thier old state into a new one by terminating their old life and germinating them with the new life of Christ that they may become the kingdom people. John the Baptist's recommending ministry began with a preliminary baptism, a baptism by water only. Jesus Christ will baptize with the Holy Ghost. John the Baptist says, "I indeed baptize you with water unto repentance: but he that cometh after me is mightier than I, whose shoes I am not worthy to bear: he shall baptize you with the Holy Ghost, and with fire:" (Matthew 3:11)