Where does the custom of bowing our heads when we hear Jesus Christ come from? Should we do it only for Jesus Christ? or Jesus, and Christ as well?
The notion of making a sign of reverence to the name “Jesus” comes from St. Paul, in Philippians 2:10. The custom of that sign of reverence being a bow of the head comes from (at the latest) the Second Council of Lyons (1274), Constitution 25:Holiness befits the house of the Lord; it is fitting that he whose abode has been established in peace should be worshipped in peace and with due reverence. Churches, then, should be entered humbly and devoutly; behaviour inside should be calm, pleasing to God, bringing peace to the beholders, a source not only of instruction but of mental refreshment.
Those who assemble in church should extol with an act of special reverence that name with is above every name, than which no other under heaven has been given to people, in which believers must be saved, the name, that is, of Jesus Christ, who will save his people from their sins. Each should fulfil in himself that which is written for all that at the name of Jesus every knee should bow;
whenever that glorious name is recalled, especially during the sacred mysteries of the mass, everyone should bow the knees of his heart, which he can do even by a bow of his head.
You bow your head at the name “Jesus” said at any time and in combination with any other words. You don’t when it is Christ or another name. You also bow at the name of Mary or when the Trinity is mentioned together.
Mary is a great woman but she is not God and you do not bow your head at the mention of her name.
Catholics (at least, Roman Rite Catholics) are instructed to do so. GIRM 275a says the following: “A bow of the head is made when the three Divine Persons are named together and at the names of Jesus, of the Blessed Virgin Mary, and of the Saint in whose honor Mass is being celebrated.”
When the
names “Father, Son, and Holy Spirit” are mentioned as a unit or in close proximity (not a title like “Holy Trinity” or “God”), you bow your head.
When the
name “Jesus” is mentioned (not a title like “Christ” or “Lord”), you bow your head.
When the
name “Mary” is mentioned (not a title like “Blessed Mother” or “Blessed Virgin”), you bow your head.
When the
name(s) of the saint(s) being honored at that particular celebration of the Mass is/are mentioned, you bow your head.
Typically (perhaps not officially), the bow of the head for the Trinity and Jesus is more pronounced than the bow of the head for Mary or another saint. For me, I bow my head nearly 90 degrees for God, and about 45 degrees for the saints. Not that I have a protractor with me. That’s just about how it is.
