The WELS has a practice that a non-WELS member cannot sing or accompany during a service. Why do you then allow non-WELS members who write hymns for the WELS hymnal? In my eyes there is not much difference between the words of a hymn on the page or from the mouths and fingers of a musician. Thank you for this ability to ask this question.
I am understanding your first sentence to intend to say that a non-WELS member cannot sing “in a way in which the person would be leading worship” – for example, as a soloist. With that understanding in mind, allow me to pass along the following thoughts that addressed previous questions like yours.
“Our hymnody would be very limited if we sang hymns composed only by Lutherans. For instance, we would be without ‘Silent Night’ and ‘Holy God, We Praise Your Name,’ both written by Roman Catholics. We would be without ‘Glory Be to God the Father’and ‘Your Works, Not Mine, O Christ,’ both written by a Presbyterian. We would lose ‘In the Cross of Christ I Glory,’ written by a man most people think was an agnostic. The test of a good hymn is not the denominational background of its author, but the confessional character of its text.
“The stanzas from ‘Amazing Grace’ that are included in Christian Worship speak correctly about the grace of God. If the text of any hymn (even one written by a Lutheran!) would contain doctrines that disagreed with the doctrines of the Bible, that hymn would not have been included in our book.
“We are not in fellowship with the Baptist Church because it teaches many things that disagree with the teachings of the Bible. But we do not consider the Baptist Church to be a non-Christian denomination. It should not surprise us, therefore, that a Baptist is able to write a hymn text that speaks correctly about grace, even though he may not be able to write a hymn text that speaks correctly about original sin, infant Baptism, or Holy Communion.
“The Lutheran Church has tended to consider or judge forms used for worship on the basis of their content rather than their source.”
A way of understanding this is that authors and composers present their works for use by Christians around the world. It is not as though the people who then use those hymns are stepping into the churches of the authors and composers and worshiping along with them. The same can be said about many of the musical pieces that our choirs use in our worship services.