In reply to Paul K..

Paul, thank you for your comment and for the helpful suggestion regarding fasting. I believe you are misinterpreting the sentence that contains the word "should," and hope you will take a second look. The authors do not say "Christians should pray more during Lent," but rather that "Christians should find ample opportunities to pray" — "should" here is not used as a verb of recommendation or obligation, but as a verb of expectation, that is, "Christians will likely find ample opportunities to pray," referring of course to the proliferation of midweek services, special devotional materials, and the like that surround us during the Lenten season.

The use of the modal verb "should" to express expectation can be seen in other sentences like: When you get to the store, you should find the potatoes in the first aisle. When you get to church, you should find Christians at prayer.