What event secured the fact that Gentiles could become Christians without being circumcised that is without becoming Jews?

The event that secured the acceptance of Gentiles into Christianity without the requirement of circumcision was the Council of Jerusalem, held around 50 AD. During this council, early Christian leaders, including the Apostle Peter, argued that salvation through Jesus Christ was available to all, regardless of adherence to Jewish law. The council ultimately concluded that imposing circumcision and other Jewish customs on Gentile converts was unnecessary, thus allowing them to join the faith freely. This decision was pivotal in shaping the early Christian movement and expanding its reach beyond Jewish communities.