Find a hip-hop instrumental. An instrumental is all the music you hear in a rap song except the vocals. You can browse instrumentals you like on video sharing sites such as YouTube and Dailymotion.
Play the instrumental and write words about your feelings toward God while listening along. After you have written a line on the page, speak your words out loud to the music and explore different pitches in your voice and different lengths for holding syllables. Experiment until you are satisfied with the line, and note what word it ends on.
Write down different words that rhyme with the last word of your line. If you end on pray, for example, write down play, day, say and pay. Use online rhyme dictionaries. Write a new line that both continues the idea of the previous line and ends on one of these rhyming words.
Continue writing lines that rhyme to the instrumental. Stop after each line and rehearse the entire rap, making changes as you go and thinking about God and what religious ideas you want to rap about. A standard rap verse is 16 lines. At this point you can stop, having written a gospel rap verse.
Rap your lyrics out loud and revise lines that sound awkward. Often a bad line can become good just by adding or deleting one word in the middle to make it flow better. Read your rap and, if you feel inspired by your spiritual words, you have successfully written gospel rap lyrics.