The following excerpt from the preface to the Trinity Hymnal–Baptist edition* highlights several important facets of hymnody. First, the theology taught by hymns have a great impact on the church's theology. For example, how do you know that Jesus is your friend? Because the hymnal tells me so! ("What a Friend we have in Jesus"). We should never underestimate the ability of hymn texts to teach. The congregation that learns of Christian joy from "Joy in Serving Jesus" is a different congregation from the one that chants "If Thou But Suffer God to Guide Thee." The preface also highlights the trend towards informal worship and has some interesting observations concerning its cause and effect.
"It is well known that the character of its song, almost equal with the character of its preaching, controls the theology of the church. In more than one communion where the preaching has departed from biblical truth the remnant of sound theology contained in favorite hymns has prevented the spiritual life of the church from becoming entirely blighted. However, as the older hymnals have become unavailable, newer editions have introduced ideas foreign to the Word of God. And, as the more formal hymnals often fail to provide hymns for informal occasions, many evangelical congregations have turned to smaller hymnals and song books. These, at best, have presented a truncated view of the place of song in divine worship, and, at worst, they have turned worship into something unworthy of a holy God and his people. There is a need for the resurgence of reverent worship of the Lord in song."
*This portion cited is from the preface to the original Trinity Hymnal.