“But my pastor says his name is Yahweh”
(A disclaimer: what follows is a bit scholarly, I hope my explanation is simple to understand. If you want a summary, look at the bottom of the page for the bottom line.)
The idea that YHWH is pronounced “Yahweh” is championed by religious leaders and experts. However, most of these religious leaders and experts will also tell you that his name is not that important!
When YHWH revealed his name to Moses, he also revealed what it means. “I am that I am (Exodus 3:14).” In Hebrew he said “AhaYaH asher AhaYaH.” The word “ahaYaH” means “I am,” or “I exist.” It is clear that the YH in YHWH is “YaH.”
“Hayah” is a form of another word that means the same thing: hawah. We know that “wah” was used as a shortened name of YHWH from a few Hebrew names. For example “Dodawah” was the father of a prophet name Eliezer, and his name is mentioned in 2 Chronicles 20:37. His name means “beloved of YHWH.” The only part of his name that is similar to YHWH is the WH at the end of his name. And how is it said? “Wah,” or “oo-ah.”
“I AM that I AM”
AhaYaH asher/hu haWaH
YaH-oo-aH. Yahuwah. Yahuah.
The pronunciation “Yahweh” is not based on the Hebrew language, or the meaning of his name. The “weh” part of Yahweh is based on a Samaritan substitution word for his name and the writings of the “Latin Fathers (2 groups that did not keep the way of YHWH).”
In the 19th century a linguist/historian named Wilhelm Gesenius (1786–1842) suggested “Yahweh” as the most probable pronunciation. Most scholars and religious leaders base their pronunciation of YHWH on his work.
1) For the pronunciation for the first part of the name he recognized that there are many names that have “YaH” and “YaHW/YaHoo” as a shortened name for YHWH.
2) For the pronunciation of the last part of the name he looked at how the “Latin Fathers” reported on Samaritan pronunciation of the name. Theodoret of Cyrus, a 5th Century Catholic leader, wrote “The Samaritans call it IABE while the Jews AIA.” Clement of Alexandria, another Catholic leader, around the year 200, said “Further, the mystic name of the four letters which was affixed to those alone to whom the adytum was accessible, is called “Iaoue,” which is interpreted, “Who is and shall be.”
So what is the problem with looking at history for the name? 1) The Samaritans, like Judaism, had already stopped saying the name of YHWH, and were using substitution words. The called him “Sema (meaning “the Name)” and “Yafe (meaning beautiful one).” Many believe that when Theodoret wrote this substitution word for YHWH into greek it came out Iabe. It is just the translation of a substitute word for the name of YHWH. 2) The oldest version of Clement’s writing does NOT say “Iaoue (Yahweh).” It says “Iaou,” or “Yah-oo.” Basing his name off of “Iaoue“ is basing his name off of bad information.
Yahweh is a name based on faulty information. The Samaritans didn’t use his name and called him Yafe, the beautiful one. Iabe (Yahweh) is an attempt to write that word into greek. Clement did not write the name “Iaoue, (Yahweh)” but instead “Iaou (Yah-oo).”
Yahweh is not a Hebrew name or word. Yahweh is not his name. It is an attempt to reconstruct the pronunciation of YHWH based on 1) the testimony of people who didn’t pronounce his name and 2) bad copies of ancient texts. The scriptures themselves testify that both “YaH” and “WaH (oo-ah)” are shortened forms of his name. The Hebrew words “haYaH” and “haWaH” both mean the same thing – I am. He told Moses, “I AM that I AM.” His name is YaHuWaH (YaH-oo-ah)! Yahuah!
“For then will I turn to the people a pure language, that they may all call upon the name of YHWH, to serve him with one consent. (Zephaniah 3:9)”
 Clement, Stromata Book V, Chapter 6:34
“Again, there is the veil of the entrance into the holy of holies. Four pillars there are, the sign of the sacred tetrad of the ancient covenants. Further, the mystic name of four letters which was affixed to those alone to whom the adytum was accessible, is called (Iaou / Iaoue), which is interpreted, “Who is and shall be.” The name of God, too, among the Greeks contains four letters.”
Note: Clement says “4 letters.” The oldest copy of this book has “Iaou,” 4 letters. The newer copies have “Iaoue,” 5 letters!