Is "In the year of our Lord" an expression of religious bias? At a Texas college those protesting its inclusion on their diplomas think it is. Does no one at that school read the Constitution or Presidential proclamations? The original Constitution ends with "Done in Convention by the Unanimous Consent of the States present the Seventeenth Day of September in the Year of our Lord one thousand seven hundred and Eighty seven and of the Independence of the United States of America the Twelfth..." Presidential proclamations even to this day conclude thus.
Supporters of the expression need to voice their arguments in the American political tradition, not in their own sectarian preference. In turn, supporters of constitutional government need to press their advantage in public and private life. Civil freedom and religious freedom are mutually reinforcing.
I might edit those diplomas, adding in the year "of the independence of the United States of America the two hundred and thirty-fourth." Hopefully that would not offend any Texans!