Tim Challies is highlighting a free to download recording of The Church's One Foundation.
His introduction spells out how important hymns are to the Church, and especially as a means of teaching. He selects Exodus 15 as an example of this latter point, which is curious. The songs of Scripture, namely the Psalms, are designed (according to the Holy Scriptures) to record, thank and praise (see Rev. Romaine's Hymns Most Perfect for more information). They are not designed to teach. That might be a side effect, but it is not the purpose of songs. The song in Exodus 15 records, thanks and offers praise. It is a proclamation relating to the specific experiences of the Children of Israel - not a homeschooling sing-song to let the kids know what is going on and why.
Is this a semantic point? No. Because some people should know better. It can be frustrating to find someone highlighted as having the biggest following for a Reformed blog like Mr Challies to be so lax when it comes to worship. The song presented is not especially bad, nor is it especially good. It is typical folksy American-style fare, over-earnest and very dull. And it is not the Psalms. I am the last person to say that Christians cannot write poems and songs for use outside of God's public worship, but there is no distinction made today, by most so-called Reformed Christians.
This criticism is intended to draw a deeper line in the sand. First, we must attend to Biblical worship. Second we must attend to what the Scriptures say about worship. Third, we must practise what we preach in worship.
Once you disperse the seemingly "innocuous" error that songs of praise are designed to teach, then you have already begun down a non-Biblical road, which will lead to the imperfect hymns of men.
Someone will say, Psalms are designed to teach.
Someone will ask for the Psalms to be made clearer.
Someone will ask to have the name of Jesus pressed into the Psalms.
Someone will then ask why bother starting with the Psalms - why not write new, better songs to teach doctrine.
And soon no one will remember the Psalms.
So it becomes a vicious circle, leading to songs which have to teach. Ignorant people need to be taught and, like children watching Barney the Dinosaur, it is decided to use songs to teach the whole Church - a Church ignorant enough to need teaching through songs but somehow bold enough to decide that it is entirely Biblical to sing whatever we want.