There are several Muslim countries that feature the crescent moon symbol on their national flag. See them and find out more about them here.
Star and crescent - Wikipedia
Flag
64 countries have religious symbols on their national flags
The Meaning of Islamic Flags - Synonym
What is the symbology of the crescent moon and stars with Islam and Middle Eastern countries? - Quora
Flags with a Crescent Moon - Flag Quiz Game - Seterra
Isolated Green Crescent Moon And Star Symbol Stock Illustration - Download Image Now - Islam, Flag, Crescent - iStock
33,000+ Muslim Flag Stock Photos, Pictures & Royalty-Free Images - iStock
Irtiqa: Eid Mubarak - with a correct New Crescent Moon
National flag of Pakistan: crescent moon and star on green background with white vertical stripe on the left side Stock Photo - Alamy