I thought arabic speaking Jews and Christians were using the term before Islam. Why should they be the ones to change?
The word “allah” has been co-opted to mean the god of Islam. I cannot imagine why any Christian would want to use that word! In a completely different scale, it is the same reason why I don’t fly a confederate flag in my front yard; I live in an area of the country where rednecks and, yes, the clan have co-opted the confederate flag. But seriously, would you call the Lord Allah and risk have people misunderstand Who you are talking about?