Why the Pharisees opposed Jesus?
The Pharisees were apprehensive about John’s baptism of repentance. The Sanhedrin was the custodian of the Jewish ceremonies and rituals. John baptized without their approval. Only Elijah, a prophet, or the Messiah were supposed to do it. So, the Pharisees questioned John through their representatives, “Why then do you baptize if you are not the Messiah or Elijah or the Prophet?” (Jn 1:25) Besides John, there came Jesus, whose popularity because of his miraculous healings was phenomenal. So, more people came to Jesus for the Baptism of repentance based on his message. That also bothered the Pharisees.
Another issue of the Pharisees was the number of disciples John and Jesus were each gaining. However, they tolerated John because he disclaimed himself being the Messiah; he was not against the Law but was only asking people for a spiritual renewal. The heightening reputation of Jesus, his “deviant” teachings that went against their practices, the immense number of people gathering around him, the increasing number of people becoming his disciples, and their transformation of life through the baptism Jesus performed through his disciples bothered the Pharisees. Since John publicly introduced Jesus as the Messiah, his listeners and disciples were turning to Jesus. This movement of acknowledging Jesus as the Messiah would become a threat to the Sanhedrin and the Jewish aristocracy. So, they wanted to get rid of him before the situation got worse.