Matthew 22: 11, 12 It was customary for wedding guests to be given garments to wear to the dinner. It was unthinkable to refuse to wear these garments. That would insult the host. The wedding garments picture the righteousness needed to enter God's kingdom - the total acceptance in God's eyes that Christ gives every believer. Christ has provided this garment of righteousness for everyone, but each person must choose to put it on in order to enter the King's dinner (eternal life). There is an open invitation, but we must be ready.
Matthew 22:15-17 The Pharisees opposed the Roman occupation of Palestine. The Herodians supported Herod Antipas and the policies instituted by Rome. Normally these two groups were bitter enemies, but here they united against Jesus. Thinking they had a foolproof plan to corner Him, together their representatives asked Jesus about paying Roman taxes. If Jesus agreed that it was right to pay taxes to Caesar, the Pharisees would say He was opposed to God, the only King they recognized. If Jesus said the taxes should not be paid, the Herodians would hand Him over to Herod on the charge of rebellion. In this case the Pharisees were not motivated by love for God's laws, and the Herodians were not motivated by love for Roman justice. Jesus' answer exposed their evil motives and embarrassed them both.
Matthew 22:21 Jesus avoided this trap by showing that we have dual citizenship (1 Peter 2:17). Our citizenship in the nation requires that we pay money for the services and benefits we receive. Our citizenship in the kingdom of heaven requires that we pledge to God our primary obedience and commitment.
Matthew 22:23 After the Pharisees and Herodians had failed to trap Jesus, the Sadducees smugly stepped in to try. They did not believe in the Resurrection because the Pentateuch has no direct teaching on it. The Pharisees had never been able to come up with a convincing argument from the Pentateuch for the Resurrection, and the Sadducees thought they had trapped Jesus for sure. But Jesus was about to show them otherwise. ( see 21:31, 32 for Jesus' answer.)