Ideas about the Kingdom of the Heavens around us and the unity of believers in Christ within it
Christ is not divided. But historically Christianity has been divided into groups following human leaders, past or present, ahead of Christ. The solution is an individual one, letting God perfect our unity with our brothers. It cannot be imposed by a human leader or organization.
Titus 3:10 instructs whenever a divisive person approaches ME and tries to start an argument, I am to warn them twice about their behavior and then excuse myself. Thereafter I should ignore them, until they repent of their argumentativeness. It is a simple instruction by which I can avoid being influenced by divisiveness. It is not an instruction to the Church or the State to burn heretics.
In Galatians 5:17-23, “heresies” are one of the works of the flesh–something we do, not something we believe. These works are opposed by the fruit of the Spirit.