What does the Bible say about deception in Christianity?

In 2 Thessalonians 2:8-12, the Apostle Paul warns that before Christ's return, there will be significant deception, particularly within the context of false Christianity. Jesus Himself noted that many would come in His name, claiming to be the Christ, and would mislead many (Matthew 24:24). This deception is characterized by a blend of truth and error that can lead even the elect astray if it were possible. Therefore, believers are urged to discern carefully between the true gospel and false teachings, as the deceivableness of unrighteousness is a prevalent theme leading to spiritual danger.