It is difficult for you to understand how certain festivals are celebrated by different communities. Living in a closed society has its own drawbacks. The problem also exists if you live in an open society with a closed mind. I dont know what is your case.
In the southern state of Kerala, Onam is celebrated by all communities. It is traditionally a hindu festival but it is celebrated by everybody including muslims. We are a christian family and have been celebrating Onam for generations now. It is more of a community festival rather than a religious festival.