I so appreciate and hear your heart’s desire shining through your post–your compassion, your desire to do your job well, your fear that the stakes are so high if you make a mistake. I want to hasten to say that I am not the expert in all of this. I am a person with lived experience in some of these areas (but not all). And each of you is a person with particular lived experience as well. We are all “living human documents” and as such we can all relate on that most basic of human level, which is how we truly connect with each other. In the end, the connections are more important than the differences. We still of course need to recognize and honor the differences, especially as they represent different spiritual needs. But the commonalities are the most crucial.
I guess my biggest concern is that you fear making a mistake as a representative of God. None of God’s representatives are God, for sure! But as I read what you have posted today, I am convinced that no one would get the impression that “God must not care” even if you used the wrong pronoun or made some other faux pas. Because your heart is one of compassion and care. I think the difference is all in how we make the errors, and how we deal with the errors once we realize we made them.
In answer to your question, I go back to what Joy said: We use our best skills that we employ everyday. Asking everyone what name they go by is generally a safe and good practice. If someone gives us some clues in conversation that they may be a trans person, you could say “I’m very much a learner, but I want to be respectful. Help me know what pronouns you prefer, and whatever else I/we can do to make you feel safe and supported here.” Beyond that, I think we all are called to just be the best chaplains we can be.