If the amount and quality of prayer said by Americans before Pearl Harbor had equaled the amount said afterward, but prior to the Battle of Midway, is it likely that the entire war with the Japanese might have gone quite differently?

This is quite true because the American Forces were comprised of a high percentage of religious individuals and this was true of their leadership as well. The many chaplains serving the installations both on land and at sea held regular services and conducted many prayers associated with missions, and this was a decisive factor for enabling eventual allied success in the Pacific. If there had been more intensive prayer work done prior to the Pearl Harbor attack, that might have been prevented altogether, or its devastating effects minimized by having a greater vigilance and a more effective scouting and communication to reveal the threat of the attacking fleet heading towards Hawaii, and the devastating loss of men and matériel on that single day of attack could have been prevented altogether. So the balance of power would have been in favor of America from the outset instead of being delayed for many, many months because of the huge losses at the very outset.