The strength of Mary Did You Know? is in the message of the song. Read the words in verse two:
Mary did you know that your baby boy will give sight to a blind man?Mary did you know that your baby boy will calm a storm with his hand?Did you know that your baby boy has walked where angels trod?And when you kiss your little baby, you have kissed the face of God.
Oh Mary did you know?
The blind will see, the deaf will hear, the dead will live again.This song is a very powerful presentation of the gospel. It is a modern Christmas hymn, quickly becoming as popular as other classics like Silent Night and Joy to the World.The lame will leap, the dumb will speak, the praises of the Lamb.
Isaac Watts wrote Joy to the World in 1719. Many evangelicals in Watt's day opposed the writing of hymns to be sung in worship. One of those leading evangelicals, William Romaine (1714-1795), saw contemporary hymns as a departure from the Scriptural norm. Romaine believed that the decline in psalmody (i.e. "singing the psalms in worship") had gone hand in hand with the decline in "vital religion."
Romaine felt people were losing their spirituality because they were now preferring the words of man to the Word of God. He said,
“I have no quarrel with Dr Watts, or with any living or dead versifier. I would not have all their poems burnt. My concern is to see Christian congregations shut out divinely inspired Psalms, and take in Dr Watts’ flights of fancy, as if the words of a poet were better than those of a prophet." (Abbey and Overton, Sacred Poetry, pages 269-272)
William Romaine’s voice was far from being a lone one in his day. It became a running joke among English churchmen in the first half of the 18th century that ‘Watts’ hymns’ were ‘Watts’ whims’.
My point of is Christian music has always been in a state of flux. Even those who say, "It's not the style of music, but the message that matters," need to remember that churchmen in the 1700's denigrated doctrinally sound and complex hymns like Joy to the World as whims. In the end, personal taste is what drives one's enjoyment of worship. Some like classical styles of worship, others like contemporary expressions with phrases repeated over and over, while others like more doctrinally complex narratives (hymns), while some insist one should only sing the Scriptures.
In my study of church history, I've concluded that worship wars are mostly wars of the flesh and not of the Spirit.