Unsupportive friends

Hi I am new to the swinging lifestyle and have finally met a fantastic man who shares the same ideas as me on this topic. I have fantasized about attending swinging parties on my own but have never gone through with it. I know what sort of relationship I want and believe that sex can be different from a mental relationship. I am also a christian and I am nervous about my church friends finding out as they would be dead against it. I personally believe that adultery is where you have an affair behind your partner's back and that there are many christian sects that allows polygamy marriage, so I don't believe what I am doing is actually against God. I would like advice on what to say to people who may find out my open relationship and are against it.