The idea of an angry, vengeful God comes in handy when you have enemies. Because then you can imagine that God will curse them. Yet, according to the New Testament, Jesus told people to love their enemies.

And he practiced what he preached. He did it by washing the feet of Judas. He did it by not allowing Peter to kill the guards who came to arrest him, etc.

Where did some Christians get the idea that God will curse those who do them wrong? Answer: there are parts of the bible that seem to indicate that God does curse people. Which, incidentally, is inconsistent with other parts of the bible.

For that reason, you have to think for yourself. You have to consult your own heart. If you choose to also follow the bible you’ll have to ignore certain parts of it. Because you can’t love your enemies as per Jesus in the Gospels, and at the same time expect God to curse them as per other parts of the bible.

Every bible reader picks and chooses what verses to believe or to ignore anyway. Though few will admit that they do it. It’s largely done on an unconscious level. Confirmation bias is often present.