I believe that in an English if statement, using then and a comma is redundant. I have been challenged on this, told i am incorrect, and shown many examples otherwise.
If the interruption to the flow of the sentence is but slight, the writer may safely omit the commas.
While the book does not list the rule, the style of the book itself shows its application. I feel vindicated...and terribly ashamed at my egregious use of commas.