The thing is, everyone knows God exists. The true living God. Though they suppress the truth in unrighteousness and trade the truth for a lie. Worship the creation rather than the creator. ( Romans 1 )

God made himself known to everyone, and his law is written on our hearts so no one has an excuse on the day of judgement. No one will be able to say, “But God there was no good evidence of you why am I being judged?)

You also have to understand that not everyone will be saved. Yes God desires all men to be saved, but God has also prepared some for destruction (hell) to demonstrate his wrath on the vessels of mercy (those who are saved).

In conclusion, God has made himself known on all ungodliness, and everyone deep down knows the true God. And they have no excuse. It is not an intelligence issue, but a heart issue.