Why are you not ashamed of the anathemas in your creeds?
He won’t tell you so I will. Because - sincerely believing them to be true - he / they affirm them and revel in them. He / they are acting as they are expected to act, and should; having the courage of their conviction, living their faith.
A word of advice to non-trinitarian Christians: Let them.
***
The constraints of history:
The anathemas in their creeds are post-biblical, just as their creeds are.
Primitive Christianity -> biblical time frame.
Nicene Christianity -> post-biblical time frame; Council of Nicaea (AD 325) / Council of Constantinople (AD 381) / Council of Chalcedon (AD 451).
Another word of advice to non-trinitarian Christians: Do not fear or be intimidated by the anathemas contained in the creeds of Nicene Christianity.
Carefully and calmly, not under duress, examine in depth what their creeds teach us and then decide whether or not they are persuasive. If you find that they are, join them.
P.S.
I didn’t have all non-trinitarians in mind when I posted this message. I primarily taught trinitarian and non-trinitarian Christian college students, but I also taught college students who weren’t Christian. My advice to non-trinitarians who don’t identify as Christian is the same advice that I offered to non-trinitarian Christians in this post.
Among other things, I’m an educator. In other threads (and on other forums over the years) I’ve publicly advocated - with virtually no support from those who affirm the creeds of Nicene Christianity, nor from those who do not - for church history to be taught in all churches, and privately in homes.