The communion rail, also called an altar rail, was a mainstay in Catholic churches up until the ‘60s and ‘70s, when the influence of Vatican Council II, although perhaps unintentionally, caused bishops and priests to get rid of them, seeing them as a hindrance to the congregation feeling welcomed and part of the liturgy. However, the communion rail is there to remind the faithful that there is a separation between them and the priest, and between the space where they are sitting and the sanctuary. This is not done to exclude the faithful, but to remind them of the sacredness of the area where the altar and tabernacle are located and to bring them to a greater sense of reverence for and understanding of the space where they are and what is taking place.
The sanctuary, the area where the altar is located, is sacred as the area where the sacrifice of the Mass takes place and also where the tabernacle is located. It can be seen as sort of the equivalent to the Holy of Holies, the area in Jewish temples that contained the Ark of the Covenant. It was located in the back of the temple and was separated from the rest of the temple by a large veil. The equivalent of the large veil in Catholic churches that separates this sacred area from the rest of the church is the communion rail. According to Jewish law, only the high priest was allowed to enter the Holy of Holies and only once a year, on the Day of Atonement. This highlights what a sacred place it was and the communion rail in a church is meant to signify the sacredness of the sanctuary and remind the faithful that it contains the Body, Blood, Soul, and Divinity of Jesus Christ and that it is the area where the sacrifice of the Mass takes place. This also echoes the Holy of Holies, as the high priest would burn incense and offer the blood of a sacrificed animal in atonement for the sins of the Israelites inside this area on the Day of Atonement.
The communion rail also gives the faithful an appropriate way to receive Communion (hence the term communion rail) by providing them an area around the altar to kneel while they receive. Kneeling in adoration and humility in front of the God who set us free by sacrificing His life for us shows that we know who we are and that we are in need of His mercy and forgiveness. He is God, and we are not, and being separated from the sanctuary reminds us of our unworthiness to receive Him and His mercy in uniting Himself with us nonetheless.
Using a communion rail is not meant to be seen as excluding the faithful from the Mass or making it seem as if they aren’t important, but rather it is there to highlight the sacredness of the area of the sanctuary, where the tabernacle containing Our Lord is located and where the sacrifice of the Mass is offered for the people and the worship of God. Its use needs to be brought back in more churches and the reason why it is there taught to the faithful so that they may understand its importance.