The sounds of Psalm 23 is somewhere between poetry and prose – it's a lot like hip-hop lyrics, actually. Except for, you know, some slight differences in content. Some people think that hip-hop is just like poetry, and while we agree that rap can be as inventive as poetry, the sound is usually different. English poetry is traditionally not written to be accompanied by outside music, but the Hebrew psalms were, in fact, written as musical pieces, something they also share with hip-hop lyrics. When translated into English by the crew that created the King James Version of the Bible, Psalm 23 has that same half-spoken, half-sung quality as rap music. Maybe that's why the phrase, "as I walk through the valley of the shadow of death" from line 4 worked so well in Coolio's song, "Gangster's Paradise."
Like a lot of rap songs, Psalm 23 uses simple sentences structure that can be repeated over and over to build a sense of rhythm: "He maketh," "He leadeth," "He restoreth," "I shall not want," "I will fear no evil," "My cup runneth over." The psalm is made of up phrases that pair up very well with one another because they have a similar sound.
Also, because the King James Version is a translation, line breaks aren't particularly important. The six "lines" you usually see numbered in a Bible are simply divided by sentences. Line breaks are not as essential to rap, either, though they're crucial to almost all poetry, with a few exceptions (like prose poems).
So, Psalm 23 is not organized as a self-contained piece of music-in-language, like, say, a Shakespearean sonnet or an Emily Dickinson hymn. It has both musical elements and prose-like elements. The musical elements are found in the repetition we described above, the quality of the words and images, and in the use of poetic rhythm in some places. In particular, the poem uses a lot of anapests (see "Form and Meter" for more information on anapests), a very distinctive metrical unit that sounds like galloping horses' hooves. These anapests serve a similar function in propelling the psalm forward as the background beat in a rap sound does in propelling the rapper.
Finally, if you still don't believe us about the similarities between this song and rap, check out these two lines. One is slight modification of the first line of this psalm (we bolded the change), and the other is the first line of a song by Jay-Z...
Psalm 23: The Lord is my shepherd, and I shall not want.
Jay-Z, "99 Problems": I got ninety-nine problems, but a ***** ain't one.
It would make for a pretty weird song, but you could read both of these lines to the same exact beat!