"Then Jesus went from Galilee to the Jordan River to be baptized by John. But John tried to talk him out of it. 'I am the one who needs to be baptized by you,' he said, 'so why are you coming to me?'
But Jesus said, 'It should be done, for we must carry out all that God requires.' So John agreed to baptize Him." Matthew 3:13-15 NLT
John was faced with what appeared to be a contradiction. John knew that he was the one to precede Jesus' ministry. He spent his life preparing the way for Jesus. He recognized that Jesus was the judge and savior of the world.
But Jesus asked John to do something that seemed weird. The greater asked the lesser to baptize him. John tried to get out of it. But Jesus knew that His baptism had to happen at the hands of John. Jesus knew the scriptures and what needed to take place for them to be fulfilled.
John had to take a step of faith and obedience. He may not have fully understood what Jesus meant. But, he understood who Jesus was, and that was enough.
We don't always fully understand the Lord. In fact, the apostle Paul said that we live in the "partial." We need to be like John. We don't have to fully understand the "what" or "why." Knowing "who" Jesus is enough. He loves us fully. He knows fully. He can be trusted to care for us fully.