How do I verbalize "Lesson: 1 John 4:7-21"? Is it correct to say: "Today's lesson is from the first book of John, Chapter 4, verses 7 through 21"?
The most commonly accepted short form of verbalizing the references for numbered books of the Bible is:


  Today's Bible reading is from first/second/third [book name], chapter 2, verses 1 through 5.


Also common, but frowned upon and even laughed at by some, is:


  Today's Bible reading is from one/two/three [book name], chapter 2, verses 1 through 5.


If it's a numbered Epistle, I prefer to be a little more descriptive for listeners who are not so familiar with the Bible and its books.

For Epistles named for their author (1 &amp; 2 Peter; 1, 2, &amp; 3 John):


  Today's Bible reading is from the first/second/third epistle/letter of [epistle name], chapter 2, verses 1 through 5.


For Epistles named for their recipients:

If the recipient is an individual (1 &amp; 2 Timothy):


  Today's Bible reading is from the first/second epistle/letter to [epistle name], chapter 2, verses 1 through 5.


If the recipient is a group (1 &amp; 2 Corinthians; 1 &amp; 2 Thessalonians):


  Today's Bible reading is from the first/second epistle/letter to the [epistle name], chapter 2, verses 1 through 5.