Because when you operate in the public sphere, as any business does, you don’t get to discriminate. If they only host weddings for their private friends and family, no problem. If you sell your shit to the public, abide by the law of the land. Very simple. Also, that same excuse was used during apartheid and for a while after to stop inter-racial marriages. It has nothing do to with their religion in reality. We are not in the US. Your business does not have freedom of religion, or any recognised religion at all under SA law, no matter how many bible verses you paste on your marketing material. It’s a matter of principal, basically.