Why don't Catholics use the term Yahweh anymore?

Answer 1

From WikiPedia: "The term tetragrammaton (from Greek τετραγράμματον, meaning "four letters")[1][2] refers to the Hebrew theonym (Hebrew: יהוה‎) transliterated to the Latin letters YHWH. It is derived from a verb that means "to be",[1] and is considered in Judaism to be a proper name of the God of Israel used in the Hebrew Bible."

The tetragrammaton is not really pronounceable as even the Jews have no idea what the original vowel sounds were, and only the consonants remain. They were transliterated into Latin by YHWH. It is a form of the archaic verb "to be" in Hebrew, and is the name of God that He, Himself, revealed in the Old Testament when Moses asked for His name. Since that time, it has been considered the most holy thing that we, as humans, have access to, and the law has always forbid its use. The High Priest would go into the Holy of Holies once a year and pronounce the Divine Name. Since there is no longer a priesthood, nor a Temple, there is no reason to ever pronounce this name and it has been strictly forbidden by the Vatican to be used in any Catholic worship, hymnal, prayerbook, etc. out of respect.