what does the bible say?
God created mankind to reflect His glory and holiness, so our sin ignites His anger. This is because it is contrary to who He is (Habakkuk 1:13a) and to how He created us as very good (Genesis 1:31). Because He is holy (Isaiah 6:3), to maintain His holiness, He must respond fiercely and fully to sin. So, yes, when there is sin, God is very angry (Romans 1:18).
However, though God has real emotion, He expresses His emotion perfectly and completely consistent with His character. For example, God never changes (Malachi 3:6a), is holy (Isaiah 6:2a, 3), and is just (Deuteronomy 32:4). When God expresses anger, it is never a sinful, rash, or “over the top” type of anger. Instead, His emotional response to sin is perfect, settled, and intentional.
Though God will pour out His wrath against sin, we also learn that He holds back His anger out of His mercy and patience. Therefore, the anger we see now is limited—He gives us many graces in this life. However, when Jesus returns (Revelation 19:11–18), He will no longer hold back His anger. At that time He will unleash it in full, consuming all unrepentant sinners once-and-for-all.