No. Not bias. Not presupposition.
Assuming your conclusion is a specific logical fallacy, also called "circular argument" or "circular reasoning." You observe that people are kind to one another. You assume that's because God is doing that. You can do that, but you cannot use it as an argument for what you're assuming. It's fallacious reasoning. All you can reasonably say is that when people are kind to one another, you assume it's because of God.
Further, by your reasoning, when people are cruel to one another, that would be an argument against the existence of God. I doubt that you accept that reasoning, despite it being of the exact same form as yours. That is the theist's second favorite fallacy, special pleading.
And when people have no arguments other than special pleading and circular reasoning, it tells me that there is no logical basis for their position.