Funny thing about your tagline now is that ‘Humanist’ used to be a person who ascribed to the notion that man is the highest/crowning-jewel of God’s creation.
That is ironic about “humanism”. Humanists hate people. They love “humanity” in the abstract, but hate people.
I explained it to my kids this way - it has to do with where your source of truth comes from.
A theist recognizes that truth is reality as God sees it.
A humanist derives truth from human reason alone.