It's the Aleph.
Rachel doesn't have one, and the Hebrew word for God is El (Aleph-Lamed). Aleph represents a soft guttural sound to open a vowel. When the Greeks adapted the Phoenician alphabet, they took the Aleph for a vowel: A.
Now
Yael has a similar sound, but a different character: Ayin. So no God in that name either.
Does this help?
Andy ;—)