The altar rail is used by many good Lutherans as a place on which to rest their hands and arms, a crutch to help them as they kneel down, a stable surface on which to lean, and in the case of children it is sometimes used as a device on which to hang their arms like a monkey. Every case is different; it does no good to stereotype or judge. The way you choose to conduct yourself, and allow your children to conduct themselves, at the altar is your decision. Seriously. It's no skin off my nose. What I would like to do, however, is share with you my own thinking on the altar rail, and why it is that I behave the way I do around it.
The altar rail is not really meant to be a handy surface for our hands or elbows. Rather, it is a sacred object meant for sacred use. It is an extension of the altar itself. Tradition would have us treat it as we would the altar because liturgically speaking, it is, in fact, an extension of it. In this sense one may say that he has received communion at the altar. When we learn to view the altar rail as an extension of the altar we begin to understand why, in former ages, the altar rail would be dressed, or we might say vested, with a special linen reserved for this purpose. It is worth reminding ourselves also that the altar, and therefore also the altar rail, is a symbol of Christ Himself, our Sacrifice for sin. Seeing the altar rail this way is reason enough to approach it with reverence, and refrain from touching it as much as possible.
But there is another reason, and it is related to the other reason why the altar rail was traditionally covered with a linen. It was a way of helping to catch any particle of the Host or drop of the Precious Blood of Christ which may happen to fall in the course of the Communion. This linen is called the communion cloth, or the houseling cloth, and there is a rich history of its careful and reverent use in Lutheran, Roman Catholic, and Episcopal churches. Whether your church still uses this cloth, or gave it up decades ago, or the practice was never known in your parts, this tradition points us toward another reason for the traditional reverence with which the Christian approaches and behaves around the altar rail, namely, so as not to get in the way of its function of catching and holding particles of the Blessed Sacrament until the ministers of the Eucharist can tend to them. Perhaps you are thinking: surely it is quite rare that a particle of the sacred Host would fall onto the altar rail. Perhaps you are even a pastor and are thinking: I have never seen this happen. I am not here to dream up far fetched scenarios, and draw out theologies around them. My point is that if a particle of the Host were to fall, or if a drop of the Precious Blood were to fall, it would be better for it to fall unto the altar rail than onto your sleeve, or your little nephew's neck.
Both reverence for the altar rail as an extension of the altar and the sense of awe and care with which the Christian conducts himself around the Sacred Species impel me to behave a certain way at the altar rail. In particular, I have trained myself to kneel down at the rail without using the rail as an aid. I make sure that I kneel with good posture, with my hands held before me, palm to palm, fingers extended, not touching the rail. And after I have received Holy Communion and have been dismissed, I rise, again, without touching the rail, turn, and return to my place. I am not sure I have touched an altar rail in years, except in caring for the church as deacon at my former congregation.
Now clearly the aged and those with weak knees, etc., will have much more difficulty doing likewise. I do think that it would be good if we fostered this sort of reverence once again for the altar rail, and assisted those who might want to kneel but may need help in doing so.
I tend to act as though that rail were not even there. Now it is worth noting, however, that the rail also serves a very visual purpose. Namely, it helps remind us that there is a holy and sacred space at the altar. This is why we call it the sanctuary. The rail sort of marks this space. Not just anyone may approach the altar, and manhandle the Sacrament, all in the name of Christian freedom. That's not how the holy things, the mysteries of God are given good stewardship. Frankly, the rail also reminds us that the Holy Communion is closed to those outside of Christ's fellowship. There is, in other words, a boundary around the altar, so to speak. And those of us who are called to this Most Holy Sacrament are in holy communion with the sacramental Body of Christ, yet also with the ecclesial, or mystical Body of Christ (not merely with the number of those we see there on Sunday morning). And in some churches the rail is actually curved, which helps to remind us that the fellowship of the altar extends all the way around that altar, so to speak; that is, it encompasses the goodly fellowship of the saints whom we see only with the eyes of faith.
Let all these considerations be for you food for thought as you approach the altar next Lord's Day.