It is a delicate question--- Who can Commune with God? And today Catholic Bishops have been voting on this matter. The issue is this-- who is worthy to partake of the Eucharist? Should just anyone be allowed to do so? In the past, and now the Catholic Church has taken the posture not that priests should police the Eucharist or fence the table, but that all the congregation should be told in advance that in essence they must police themselves. If they are knowingly in violation of church teaching on some major matter they should not take the Eucharist. For example anyone, gay or straight who is having sex outside of Christian marriage are encouraged to abstain. Now this raises all kinds of questions.
In the first place, no one is actually 'worthy' of partaking of the body and blood of Jesus Christ. All have sinned and fallen short of the grace of God. If we waited until we were worthy we'd all still be waiting. But there is some pertinent material about this question to be found in 1 Corinthians 11. Paul says there that we must not partake of this sacrament "in an unworthy manner". Now that's a different matter than 'being worthy'. That has to do with how we partake of the sacrament, and Paul somewhat cryptically gives us another clue-- we should partake: 1) together, waiting for one another and doing it as a group together; 2) we should do it in a worthy manner; and 3) we should do it discerning 'the body'. Paul even goes so far as to say that if you violate these three rules you could get sick and die. That sounds pretty serious and drastic. Scholars have debated what 'body' Paul is talking about. In traditional Catholic theology it was assumed that this was a reference to the elements of the sacrament, but this is unlikely. For one thing where is the reference to discerning the blood? For another thing the context doesn't favor this reading of 1 Cor. 11. The 'body' here as elsewhere in 1 Corinthians refers to the Body of Christ in the ecclesiological sense--- that would be us, the church. Paul is saying that if you go ahead and take the Lord's Supper without doing it as an act of the communion of the saints, of the church itself, you have commited a grievous mistake. The Lord's Supper is not all about you and your private relationship with God. Its about your vertical relationship with God of course, but it is also about your horizontal relationship with your fellow believers as well. We have been reconciled to Christ corporately, and one of the functions of communion is to bind us to each other.
Most denominations have some sort of invitation to the Table-- ours goes back to the Anglican liturgy in which we say "all who truly and earnestly repent of their sins, and are in love and fellowship with their neighbor, draw near with faith..." John Wesley was to add to this that if one was prepared to repent and come to the table for the first time as an act of faith, even though one was not previously a Christian that that was fine-- he saw the Lord's Supper as a converting sacrament in such cases, and not just a confirming sacrament. What is however very clear from 1 Cor. 11 is that this is not a sacrament that was intended for those who "do not discern the body". Unlike baptism which is a passive sacrament, the Lord's Supper is an active sacrament, and must be consciously and actively partaken of. So perhaps now is a good time for us all to think about should and shouldn't take communion. One thing is clear to me-- this is indeed a means of grace which changes lives.
A favorite communion story. There was a Presbyterian Church in downtown Richmond where both slaves and slave owners attended before and during the Civil War. There normal practice on communion Sunday was for those who sat downstairs (i.e. the slave owners and other whites and their families) to take communion first, whereas those who sat upstairs (the slaves and their families) would come for the second call to communion. However on the Sunday after Apommattox when the first call for communion was made, an elderly African American man came down the aisle for communion, to the shock of one and all. Quickly an elderly bearded white man hooked his arm in the arm of the former slave and went forward and they took communion together. That man was Robert E. Lee, who had opposed slavery before the war, but turned down Lincoln's offer to lead the Federal forces, because he could not fight against his beloved Virginia. Communion is a means of grace, and one of the manfestations is that it is an occasion to receive and share forgiveness. Think on these things.