Jesus is the only one capable of forgiving sins. And since God requires a blood sacrifice for the forgiveness of sins, Jesus came to earth, was murdered, buried in a tomb, and then 3 days later rose back to life! That is what Christians believe. And because he died and rose from the dead - he is the ultimate blood sacrifice, and we can be forgiven because of HIM!!
On Sunday, 82 people wanted to publicly display their love for and belief in Jesus Christ. So, they were dunked under the water, and brought back up again - as a symbol of Jesus death and resurrection.
It was a beautiful day, and God was glorified.