Going to mosque for Ifaar with friends is a sin?

[viratkohli@2004]

Hello, I am a Sikh studying in the Czech Republic, and I have many muslim friends here, and over the last month of Ramadan, I joined few of them in the Mosque to have Iftar with them as a sign of respect and not with the intention of giving up my Sikh beliefs and morals, and similarly I hosted an Iftar for them as well. Now 2 days ago I was accused by the only other Sikh in my University that I had committed a sin by entering the mosque based on the fact what Muslims have done to us? This has been bothering me because I thought the whole basis of our religion is treating everyone as equal and respecting all beliefs in an holistic approach. Am I in the wrong?