[Pietro]

"It's this professors decision on who gets letters of recommendation from him."

I agree w/ your position but, shouldn't his letter of recommendation at least take into account the quality of work the student produced in this professor's class?

If the student aced the class, the professor should not withhold that information. Adding an extra-curricular requirement involving "belief" smacks of academic manipulation.

And that's petty.

[discostu]

It should, but it's his letter. It's a matter of freedom of association, as long as his conditions aren't immoral/ illegal he's free to have whatever prerequisites he wants. Now his collegues at higher levels will learn about them soon enough and his letters of recommendation will gain or lose value because of his conditions.

Letters of recomendation are a tool of academic manipulation, as well they should be. Basically when you go to a professor and ask him for his recommendation to help you get into a high quality school you're asking if he feels you are worthy, if he wants you to possibly become a collegue. His reasons for saying yes or no may be petty, but remember the student instigated this by asking the question.