Communion is not just a meaningless ritual. It is full of very deep meaning that goes to the very heart of the Christian faith.
My church is open, meaning that anyone of any faith may partake. But there is also a qualifier; when the pastor gives the invitation, he includes that ANYONE WHO BELIEVES is welcome. It doesn't matter if you're UCC, Roman Catholic, Baptist, Episcopalian, Presbyterian, independent, or what, but we do ask that you believe.
Now, we're not going to question you when we pass you the plate or you come up to the altar, but by accepting it you are acknowledging that you share our faith and our belief in Jesus Christ as Saviour. If you do not so acknowledge, then it is hypocritical and exceedingly disrepectful of you to demand that you be allowed to participate.
Because the law of this country keeps church and state separate, the church is permitted to "discriminate" against those who do not share our faith when it comes to participation in our most holy ritual. You will not find a law anywhere in this country that grants you the right to force a church to waive their beliefs and requirements in favor of your "comfort".