Love these types of discussions. My question would be this.
What constitutes an "old hymn", and what about "new hymns"?
What about "old hymns" that are arranged a little differently musically, but keep the same
lyrics?
I was going to say good questions...but then I reconsidered...When I'm preparing music each week for my churhc, I don't think those questions matter hardly at all. What matters is...
-Is it true Biblically?
-Is it true to human experience? (Does it say we won't have any trouble if we just trust Jesus? If so, that's not really true is it?)
-Is the melody Singable by musically untrained people? (this does, by default eliminate a lot of contemporary hymns, and some older hymns as well)
-Are MOST of the songs we are singing familiar to most of the people, so that they don't feel lost?
-If people only heard the music and no preaching, would they hear the Gospel of Jesus and his cross?
WHEN the song was written has almost ZERO bearing on whether or not a song is sung in our church. An average sunday includes 6 songs total, and that may range from 4 older hymns/ 2 newer hymns...to 1 older hymns, 5 newer hymns.
(BTW, I'm intentionally calling all these songs hymns because the longest and oldest definition of a hymn is simply "sung praise to God". So in the 1600's, no matter what musical stye you wrote in, if you wrote a song to God for church use, it would have been called a hymn. So, "A Mighty Fortress" is a hymn...and David Crowders "You Alone" is a Hymn, it's just a new one)
Finally, regarding Older Hymns done in a different style...I generally think it's best to keep the melody the same...altering the accompaniment will not make the song impossible to sing for someone who has grown up singing it.
If you want to change an older hymn, just take the text and write a whole new melody...but if you just start altering the melody slightly hear and there, you make it hard on those who know a hymn well.