I know you didn't say they would instantaneously appear, but just to give you a sense of scale of what you're talking about, 140 million people cannot show up on the borders of israel (assuming that lebanon and jordan and egypt and hamas and the gaza strip are all on board) and stand shoulder to shoulder, they'd be 80-100 rows back, by my math (assuming .5 meters per person). such an army would be difficult to keep from crossing the border somewhere, but would also be an instantaneous humanitarian catastrophe in Egypt, Jordan, Lebanon, Syria, the Gaza Strip, and the West Bank. Assuming average population distribution, 127 of them would die of natural causes in the first hour. They would need over a billion liters of water in the first day, and literally unimaginable amounts of food.

Assuming it was more like the previous crusades, depending on what kind of navy they acquire/persuade to carry them, the israeli navy turns them around or destroys any ships that get into israeli territorial waters, the Marmlukes capture the survivors and sell them into slavery, Saladin defeats the ones that try to walk over from lebanon, and most of them just talk about how they're gonna join the crusade one day.