"When we start making the Eucharistic meal something to define membership instead of to proclaim grace and gift, we always get in trouble; that's been the temptation of every denomination that has the Eucharist.
Too often we use Eucharist to separate who's in from who's out, who's worthy from who's unworthy, instead of to declare that all of us are radically unworthy, and that worthiness is not even the issue. If worthiness is the issue, who can stand before God? Are those who receive actually saying they are 'worthy'? I hope not. It is an ego statement to begin with.
The issue is not worthiness; the issue is trust and surrender. I think that explains the joyous character with which we so often celebrate the Eucharist. We are pulled into immense gratitude and joy for such constant and unearned grace. It doesn't get any better than this! All we can do at Eucharist is kneel in gratitude and then stand in confidence.
Actually, St. Augustine said that the proper Christian posture for prayer was standing, because we no longer had to grovel before such a God or fear any God that is like Jesus."
Fr Richard Rohr