In terms of "is it ok" do you mean is it accepted?
YES!!! Anything is acceptable for you to wear to your wedding, no matter the setting. That is why it is YOUR WEDDING, your dream day. The only thing you have to keep in mind is what the rules of the church are. Many churches have their own rules for attire, photography and decor and this may be something to keep in mind when planning your wedding day. First, prioritize what is more important to you, a specific venue that you can not get married without or the dress of your dreams that can't be compromised. If you want the black wedding dress, double check that your venue allows it before you confirm that venue and/or before you sign a contract on the gown.
It wouldn't be weird that your groom has a black suit on because it ties the two of you together and it's not like you two have matching gowns on, so you will each be able to stand out on your own and as a newly married couple.
My relative got married in black and it was beautiful and she was able to wear her gown again on their 1st anniversary because it wasn't the traditional white dress.
Most of all remember - THIS IS YOUR DAY, DO IT YOUR WAY! Congrats and have a BLAST!!!