Being a Muslim, I would like to say that what Imam Bukhari said is his perception of Vande Mataram. Singing Vande Mataram won't change my religion and I would be proud to sing it alone, in school or anywhere with the masses.
Rather it should be made the national anthem instead of Jan Gana Mana.....which was penned down in praise of George V.
So, bottomline is that singing few lines in praise of your country won't change your religion and I am proud to be an Indian as much as anyone else is.