Here is something that Pope Pius XI said about Christianity in Mit Brennender Sorge;
9. Beware, Venerable Brethren, of that growing abuse, in speech as in writing, of the name of God as though it were a meaningless label, to be affixed to any creation, more or less arbitrary, of human speculation. Use your influence on the Faithful, that they refuse to yield to this aberration. Our God is the Personal God, supernatural, omnipotent, infinitely perfect, one in the Trinity of Persons, tri-personal in the unity of divine essence, the Creator of all existence. Lord, King and ultimate Consummator of the history of the world, who will not, and cannot, tolerate a rival God by His side.
10. This God, this Sovereign Master, has issued commandments whose value is independent of time and space, country and race. As God's sun shines on every human face so His law knows neither privilege nor exception. Rulers and subjects, crowned and uncrowned, rich and poor are equally subject to His word. From the fullness of the Creators' right there naturally arises the fullness of His right to be obeyed by individuals and communities, whoever they are. This obedience permeates all branches of activity in which moral values claim harmony with the law of God, and pervades all integration of the ever-changing laws of man into the immutable laws of God.
11. None but superficial minds could stumble into concepts of a national God, of a national religion; or attempt to lock within the frontiers of a single people, within the narrow limits of a single race, God, the Creator of the universe, King and Legislator of all nations before whose immensity they are "as a drop of a bucket" (Isaiah xI, 15).