What are your main religious observances?

I run a Facebook page in a very diverse cultural and religious country and want to be inclusive of all regions when wishing people well for like Easter and Ramadan and Shavouth and all that, but between all the faiths there are SO MANY holidays that we'd end up just posting religious posts all the time!

I wanted to find out which is the most important days to observe in your religion so I can focus on those?

Thank you for your help!