It is illegal. As good as this idea is, and as helpful as it would be to teach the music to members of the choir, such duplication without permission is against the law. Write or call the publishers of the music. They will inform you of their requirements concerning your request. Duplication of copyrighted materials is against the law when the purpose avoids a legal purchase.
Embarrassment is the first.
Additionally, the law provides for the owner of a copyright to recover damages for unauthorized use of copyrighted music. Churches, schools and not-for profit organizations can be infringers, too. Professional musicians in most schools and churches know the reasons for the law and therefore would not derive satisfaction from doing something against it. Such action forces the price of legal editions higher. Perpetrators risk dishonor from professional colleagues who understand the law.