You have to hear this. The first ever rap about the Heidelberg Catechism (a historic Reformed confession).
To listen, go here. You'll have to look at the post to see where to click and listen. The lyrics are printed on the blog post from C.J. Mahaney. The artist is Curtis Allen, a.k.a "Voice". As a former rapper myself, I can say this brother is a solid lyricist. Check out his album here.
HT: Jersey Jeff