God in Islam and afterlife

Most of the people who reject God say that they don't have enough "evidence". For example, today, if anyone sees something supernatural, he will be 100% sure that God exists! Like, some dead person coming back to life & talking with Atheists or an angel talking with someone. Keeping the aforementioned point in consideration & also that, **the people who came before us were also Humans like us**: 1 - Abraham was a messenger of God & he talked with angels! From my view-point, isn't it enough proof of God existence or whether there is infact an afterlife or not? Why he still asked for a proof of afterlife when he was talking with God himself? 2 - God spoke directly with Moses & commanded him to go to Pharaoh, as Surah Taha tells us. Then, how come Moses was still saying that "**he is afraid of Pharaoh or that he might not succeed or that he might kill him**"? I can't even imagine someone talking with the God himself & he is afraid of being killed or that he might not succeed? (I know someone will say that was their Human nature but the point is, they were talking with the God himself or with angels.)