An example question can be found here, which contains an image of a painting of the (according to the asker) "Mother of God". While the term is certainly embraced by Catholics, it is utterly unheard in most Protestant denominations and even idolatrous to many Christians. In the interest of neutrality, and since the question isn't a discussion of the term, or even about Catholicism or Mary the mother of Jesus, is the use of the term in the title and question appropriate?
Does the term convey an unambiguous meaning? I think so. Even Protestants who view the term as idolatrous will understand the meaning, and I think only the most hyper-sensitive types would take offence at that term in the question.
So my vote: Leave it there. It's not harming anyone.
In some other cases, where a term may have an ambiguous meaning, or is overtly offensive, it may be more appropriate to consider changing the wording. But I don't think those issues apply here.
Ideally the title of the question should be something that is searchable. There's a good precedent for it in identification questions on [gardening.se] and even in the video games site with half-remembered games and the sci-fi site with half-remembered movies.
The title should have been changed to something concerning what's in the picture. "What is this image of a poor mother and child?" very simple, very useful!
But the intentional use "Mother of God" should not be edited for any reason unless used in vain. She is our sweet and tender mother and if someone chooses to show their love for her, even on a PC network that is 90% Protestant, changing how someone shows respect for their mother is reprehensible.