Why were the Judaizers ready to kill Christians?

The Judaizers were so completely wrapped up in their Old Testament religion that they were ready to kill anyone who opposed them. Their religious zeal made them vicious, and they saw believers in Jesus as opponents of their faith, so they imprisoned and put them to death.

Les explains that the Judaizers were so wrapped up in their Old Testament religion that they were ready to kill anybody that opposed them. He stresses that no one is so vicious, and no one so ready to kill, as a religious person—that is religion, not Christianity. Paul himself, as a Judaizer, thought he ought to do many things contrary to the name of Jesus of Nazareth. He shut up many of the saints in prison, having received authority from the chief priests, and when they were put to death, he gave his voice or vote against them. Their religious commitment drove them to violent opposition.

What were the Judaizers ready to do to anyone who opposed them?

The Judaizers were ready to kill anyone who opposed them. They were so wrapped up in their Old Testament religion that they would put to death those who opposed them, including believers who confessed Jesus as the Messiah. Paul himself testified that he voted against such believers when they were put to death.