I am a converted Catholic from a non-practicing Christian family. My brother has asked me to be in his wedding, but I politely declined, stating that it is against Catholic teaching. I know that it is an invalid marriage because it is being held outside and I do not know who is marrying the couple. Does the Church view all non-Catholic weddings as invalid because they are not officiated by a priest? Can you give me some advice on how to explain this to my family?
Assuming that the bride and groom are both non-Catholics and that there are no obvious impediments to the marriage (e.g., previous marriage, close blood relationship), the Church will presume your brother’s wedding to be valid and, if both parties are baptized, sacramental. Non-Catholics are not bound by the Catholic rules of marriage and so are able to marry in rituals and locations that are otherwise not ordinarily allowed to Catholics.