One of my many previous jobs in my life was as a classical radio announcer. After a year or two working the Saturday afternoon pre- and post-opera broadcast shift, I actually got to move into the weekday morning slot, at the point the principal live local broadcast at this particular public radio station attached to FSU, where I was doing my graduate work. It was actually a pretty good situation for me; It got me up early and thinking about music for three hours, after which I went home and wrote on my dissertation. In truth, if it had been possible to make a living doing that, whether there or elsewhere, my life might have taken a completely different path. I think I was pretty decent at it.
Beyond the straightforward playing of classical music (mostly from CDs at that time with some LPs), my job also included the occasional live on-air interview, mostly with local musicians but occasionally pre-recorded interviews with more national or even international figures (I think the conductor Robert Shaw, who regularly came to Tallahassee for performances with the local community chorus, and the violinist Gil Shaham was probably the most famous musician I interviewed).
One interview I remember at least for a particular moment was with one of the associate deans at FSU at the time, who also worked on the annual festival of new music at the school. Now for those who are not terribly familiar with the classical music world, it helps to know at this point that when it comes to a very large part of the classical music spectrum, the church can look like a radical avant-garde movement by comparison. For an awful lot of listeners and not a small number of performers, even with only three letters, "new" is a four-letter word. Playing particularly avant-garde works on the air simply didn't happen, because the powers that were didn't want to put up with the virulent and potentially violent blowback that would result.
The task in this case became to convince listeners that a new music concert didn't necessarily mean a barrage of atonal fright sounds. I remember floundering around for a bit before finally putting the question forward for the associate dean to answer: "OK, is this concert about new music or (air quotes only visible in the studio, dramatic vocal register change, words run together) newmusic?"
There can be similar reaction to the introduction of a new hymn or song in worship, at least in some cases. Here, though, the discussion is complicated by the division of labor in congregational singing. Remember, the technical meaning of the term "hymn" encompasses the text being sung, with the music to which it is being sung being identified as the "hymn tune." While songs in more contemporary genres of church music tend to be more fixedly associated in tune and text, hymns have the inherent possibility of being sung with more than one hymn tune. Admittedly no one is ever likely to set the tune NEW BRITAIN, the one most commonly assocaited with "Amazing grace," to any other text, it could be done. Many writers of new hymns take advantage of this by writing new hymns that can be sung with already-familiar tunes. Not being a composer by any means, I am among this number when I engage in hymn writing. It's not that I have any problem with a tunesmith creating a new melody for anything I write, but I can't do it myself and attaching a familiar tune makes the hymn more accessible more quickly.
At any rate, a good marriage of a new hymn to a familiar tune can ease a lot of the apprehension about singing something new. In a sense, the new text is eased into the minds and mouths of the congregation by the tune.
Still, the advancing of new tunes as well as new texts needs to be a part of a congregation's worshiping life as well. There is too much risk of stagnation without some infusion of new musical life. Furthermore, God did not quit inspiring composers after 1900. God gives creativity as a gift to many different kinds of artists, and those who choose to use that God-given creativity to compose new music for the church should not be met with indifference and point-blank rejection.
Furthermore, a church that can only repeat and parrot words (or tunes, for that matter) decades or centuries old is dying. There it is. Ancient truths speak in new words and sing in new tunes, presenting to every generation in words and music that arrest the attention and provoke the soul to new heights of praise and new depths of understanding. Cutting itself off from that is just a good way for the church to go stale and lifeless.
Make use of your instrumentalists, dear preacher, in first of all determining the singability of a new tune for your congregation, and of all your musicians in teaching the tune to the congregation. Give it time to be heard and let the congregation join in as ready, at least the first time a new song is introduced. These are fairly basic steps that help take away the fear of the new, or at least calm it just a little.
But singing something new - not everything, but something - is vital for the life, energy, imagination, and intelligence of the church. For goodness's sake, don't choke that off.
Mind you, in some styles new music is actually welcomed and craved...