Dear Rabbi,Where does the halacha for kiddush levana (blessing for the New Moon) come from, and have there been any Torah authorities who were opposed to it?
The source for blessing the new moon comes from the Talmud. To my knowledge, there have never been any Torah authorities who opposed it.
I assume that your question is based on the misconception that sanctifying the moon bears a resemblance to moon-worship. This is incorrect. We are not worshipping the moon; rather we are praising G-d for His marvelous creations, including the miracle of the moon's monthly rebirth. One of the principal ways to recognize G-d is through His works; the immutable monthly cycle of the moon is one of the more visible aspects of G-d's masterful creation.
Additionally, the relationship between G-d and the Jewish people is compared to the relationship between the sun and the moon. The sun is the source of the light radiating from the moon. The extent to which the moon “turns its face” to the sun, that radiance is visible to others. When the moon “turns away” from the sun, it is cast into darkness. So too, when the Jewish People turn away from G-d, they weaken and wane. When they return to G-d, they reflect His luminescence and wax to become “a light unto the nations”.
Therefore, specifically at the time of the new moon – a renaissance of return and rejuvenation – we turn our faces upward to G-d – and view the monthly rebirth of the moon as a symbol of G-d's promise to ultimately redeem the Jewish People and make us whole again, such that we can reflect His Divine Light into the world with full radiance.
- Talmud Sanhedrin 42a