There’s a time and a place for everything. If you have not been invited to this ceremony and reception, you should not presume to “appear” merely on the basis of living in the neighborhood. If you have been invited, declining the invitation and not attending either the ceremony or reception is sufficient.
While your desire to evangelize these people with the truth of the Catholic position on homosexuality is commendable, charity demands taking into consideration whether a particular means of sharing the truth is likely to be helpful or to drive others further away. In my opinion, attending a party merely so you can share unwanted truths with people is not likely to be helpful. At the very least, you probably will be asked to leave.
