The Mishna in Talmud Sanhedrin 55b teaches:
“The blasphemer is not liable to execution-unless he pronounces the Divine Name.”
Rashi states that the Divine Name would be the Specific Name of G-d: The Tetragrammaton Yud-Heh-Vav-Heh.
It is forbidden to pronounce the Name by its letters.
Not only Jews are prohibited to pronounce G-d’s highest Name but also Gentiles. A Gentile is liable to execution under Noachide law for blaspheming any seven Names of G-d that may not be erased (see Rambam, Mishna Torah-Hilchot Yesode’i HaTorah 6:2). I am going to write a further article on the exact statement of the Rambam in Hilchot Yesode’i HaTorah!
A Mishna in Talmud Sanhedrin 90a teaches that “All Israel having a share in the World to Come (Olam HaBah)”. Even Jewish sinners have a share in the World to Come. However, the same Mishna also lists those people who do not have a share in the World to Come because of certain wrongdoings. And also here, the Mishna is referring to Jews. By the way, according to Judaism, also Gentiles have a share in the World to Come. Nevertheless, this Mishna here in Sanhedrin 90a is referring to Jews only.
Jews who say that there is no reference to the Resurrection of the Dead (Techiat HaMetim) or that the Torah is not from Heaven, etc. have no share in Olam HaBah. Abba Shaul says: Also one who pronounces the Name of G-d according to its letters.
The Name E-L represents strict judgment. The Tetragrammaton represents G-d’s attribute of mercy. The world could neither exist without mercy nor without judgement. The two attributes have to be balanced. Otherwise the wicked would be never punished (if there was only mercy) and there would just be no difference between wicked and righteous. G-d therefore relates to the world with both attributes at the same time.
The highest Name of G-d Yud Heh Vav Heh was only pronounced by the Cohen HaGadol (High Priest) inside the Holy of Holies (Kodesh HaKedoshim) inside the Temple.
The Rambam (Maimonides, 1135-1204) writes in his Moreh Nevuchim-Guide for the Perpexed, 1:61
All the Names of G-d that can be found in any of the books derive from His actions. There is nothing secret in this matter. The only exception is one Name: Yud Heh Vav Heh. This Name has been in existence without any derivation. Meaning that this Name is an indication of His essence.