No president of ours needs to know one sentence from the Koran.
I would disagree. Know thine enemy.
Knowing the Quran worked out well for Thomas Jefferson. It made it clear in his mind why we needed to go to Tripoli and reduce their numbers and influence.
In a certain sense, you are right: no president, and even anyone else, really needs to know one sentence of the Quran. Nothing beneficial can be withdrawn from that book! However, if our enemies believe the teachings of the Quran and will obey them, we need to be prepared to respond adequately. Not trying to know what our enemies really believe (from the Quran and Islam), and what evil they may attempt to do against us, is quite irresponsible, especially for a wise president! We need to have a president who understands well our enemies and who is fully ready to fight back. When I say that our president must understand well our enemies, I do not mean that he must agree with them or call them our friends, but rather that he must know where they come from (they have been poisoned by the Quranic teachings), and what they may do against us (attack us because they classify us as infidels).
The Founding Fathers already weighed in on Islam.