After the closing credits of episode 10 of Devilman: Crybaby, the series ends on an image of a reformed Earth with two moons.
Why does Earth have two moons at the end of Devilman: Crybaby?
After the closing credits of episode 10 of Devilman: Crybaby, the series ends on an image of a reformed Earth with two moons.
Why does Earth have two moons at the end of Devilman: Crybaby?
The two moons are the two halves of the old moon split apart in the final battle.
This happened during the season finale but can also be seen in the ending credits and is alluded to in the opening. It holds symbolism for the main conflict of the show between Akira and Ryo. It also ties in with other works in the series as mentioned by @Sn0wCrack.
The new moon seems to be a chunk of the old earth, the first episode's introduction scene where God is destroying earth we see this pretty easily illustrated.
Earth Before:
Earth After:
And since this same event occurs during the end of Devilman: Crybaby, it's safe to assume this is the cause of the second moon during the post-credits sequence.
As for a reasoning on showing this with such prevalence (light spoilers ahead): a lot of elements from the Devilman: Crybaby adaptation actually come from the "fleshing out" (or more accurately "hinting at") of the timelooping themes of the later Devilman Series works, namely the few Devilman "sequels", such as Violence Jack and Devilman Lady (simply Devil Lady in English).