Why do believers face persecution according to the Bible?

The Bible teaches that persecution is an expected reality for believers, as seen in Galatians 4:29. Just as Ishmael mocked Isaac, those who rely on their own efforts often oppose and persecute those who are born of the Spirit. This illustrates a broader spiritual conflict between the earthly and the heavenly, where the gospel's radical grace dismantles human pride. Jesus Himself warns that 'in this world you will have trouble,' signifying that suffering for faith is a mark of authenticity in the life of a Christian. However, this also serves to refine believers and strengthen their reliance on Christ.