Been a pastor for 44 years (PCUSA kind) - have given many an invocation in all sorts of settings from city councils to state legislatures. Early on, I made the decision to honor all faiths and keep my prayers free from specific religious references.
It's easy to compose a non-sectarian prayer that honors whatever deity one's invoking and respects all who are present.
Obviously, even the most neutral of all prayers is likely to reference some divine element, even if prayers are addressed to the earth, the universe, or to one's pet turtle.
Christian pastors who refuse to honor those present and choose to make prayers pointedly "christian," are choosing to be offensive in the worst kinds of ways.
While congratulating themselves for their courage, they're really thoughtless - rather than honoring Jesus, they're using him as a sledge hammer to further their own sense of power.