The New Testament talks about the attributes of God. Kind, gentle, patient, loving, caring, forgiving, and the list goes on, and on. But how do the writers of those books know this?

They were in Jesus's presence. He demonstrated these attributes to them through the way He lived. They had knowledge of these attributes because they experienced them.

When people experience my presence, what attributes do they see? Would they call me patient? kind? gentle? loving? I dont know, but i doubt it. Maybe shy, or quiet, but probably not patient, loving, or gentle. If I'm lucky they'd call me a servant. Maybe.