Muhd

Further, anyone familiar with the biblical Thomas would never think "doubting Thomas" referred to anyone other than the apostle Thomas. At least, I wouldn't.

@Mr.ShinyandNew安宇 Anglicans are a rare exception to Protestants generally, who make a point of referring to apostles by only their names. If you look at the discussion in this thread, it's pretty clear that the nations where saint thomas is used in the expression are historically Catholic nations, and the ones where it is merely "Thomas" are historically protestant nations.

This is almost certainly due to protestantism and/or convenience, not secularization.