"If we let him go on like this, everyone will believe in him, and then the Romans will come and take away both our temple and our nation." — John 11:48
Jesus' popularity with the people had become a matter of great concern among the ruling Pharisees and priests in Jerusalem. Why? Because he had raised Lazarus from the dead! (See John 11:17-44.)
A number of Jerusalem residents had visited nearby Bethany to pay their respects after the funeral for Lazarus, the brother of Martha and Mary. Then they had watched as Lazarus, who had been dead for four days, walked out of his tomb alive when Jesus called his name. As they returned home, some of them shared this news with Jerusalem's religious leaders.
And those leaders felt threatened, thinking that too many people had begun to believe in Jesus. So they called an urgent meeting. It wasn't that they denied Jesus' miracles; they just didn't want to lose their influence with the local power base.
See, the priests were not only religious leaders but also allies of Herod's dynasty, powered by the Roman Empire. They profited from the business of the temple complex. So they saw the popularity of Jesus as a threat to their political and economic power base. And they believed that holding on to that power was essential for the people's survival. So, together with the Pharisees, they plotted to murder Jesus.