By Bush Family, you mean his parents. I believe the reason he attends St. Johns is because of its convenience to the White House, and they are very used to having Presidents and other dignitaries in attendance there. I don't think he thinks of himself as an Episcopalian or a Methodist; that is my impression. I think Evangelical Christian is the applicable term in his mind, which you mentioned.
"By Bush Family, you mean his parents. I believe the reason he attends St. Johns is because of its convenience to the White House, and they are very used to having Presidents and other dignitaries in attendance there."
Indeed, St. John's is nicknamed "The Church of the Presidents" and there are kneelers with various Presidents' names needlepointed on them. It's worth taking a few minutes to tour the inside when visiting D.C. Beautiful stained glass windows.