Protestants make the best ecumenists. We aren’t absolutely invested in our traditional formulas, and we are always going back to the great consensus document of the Christian church, viz., the Bible.

Conversely and for the same reason, ecumenists in more tradition-bound traditions become more Protestant. It’s no accident that the great ecumenical Catholics of the last century were deep students of Scripture like Congar and de Lubac, not to mention John Paul II and Benedict.