Sentence:  In this connection , it has been observed that the increasing number of Irish Catholics , priests and laity , in England , while certainly seen as good for Catholicism , is nevertheless a source of embarrassment for some of the more nationalistic English Catholics , especially when these Irishmen offer to remind their Christian <WSD>brethren</WSD> of this good . 
Meaning of the word marked with <WSD> tags:  a male person who is a fellow member (of a fraternity or religion or other group)