People need to understand everything on its own merits, the Bible included.
The Bible sees slavery as totally okay, and the only form of government mentioned in it is hereditary monarchy. It is a document from a past time.
Jesus clearly said when he would return, and then he did not show up.
First he said that he did not know the day or the hour, but that God the Father did. So Jesus admits that he does not have the knowledge that God does.
Then he said that he would surely return before the last of the group he was speaking with had tasted death. (a rather strange metaphor).
So either Jesus did not actually appear as he promised, or there is a disciple still around after about 2000 years.
There is nothing more to comprehend about this. Jesus said what he would do, and then he did not do as he promised.
Paul thought that Jesus would pop up very very soon. But again, he did not.