Is it permissible for a Muslim to attend a meal gathering hosted by non-Muslim relatives (my brother's wedding) in a place where alcohol might be served?

Participating in religious matters of non-Muslims, such as attending services in a church, is among the major sins and may even amount to disbelief (kufr). As for participating in a banquet where wine is suspected to be present, it is forbidden and a major sin, due to the Almighty’s saying: "So do not sit, after the remembrance, with the wrongdoing people," and the Prophet’s (peace and blessings be upon him) saying: "Whoever believes in Allah and the Last Day should not sit at a table where wine is being drunk." Such participation contradicts changing evil with one's heart. Furthermore, compromises in religion weaken the position of the caller to Islam and make him lose credibility.