The Christian pastor hosting the Islamic Imam suggests that Muhammad collected followers because they thought the strength of his armies may indicate the truth of what Muhammad preached.
I'm more persuaded that they were men that didn't want to work for a living but instead wanted to live off of the fruit of the labor of others, or "spoils of war booty" (including their women) as the Quran's chapter title highlights, that was stolen from the innocents that they attacked and vanquished through imperialistic conquest.
http://www.petewaldo.com/banu_qurayza_massacre.htmQur'an 33:26 "
Allah took down the People of the Scripture Book. He cast terror into their hearts. Some you slew, and some you made prisoners. And He made you heirs of their lands, their houses, and their goods, giving you a land which you had not traversed before. And Allah has power over all things."
Ishaq:465 "
Then the Apostle divided the property, wives, and children of the Qurayza among the Muslims. Allah's Messenger took his fifth of the booty. He made known on that day the extra shares for horses and their riders - giving the horse two shares and the rider one. A Muslim without a horse got one share of the spoil. It was the first booty in which lots were cast."
Ishaq:204/ Tabari VI:134 "'
Men of the Khazraj, do you know what you are pledging yourselves to in swearing allegiance to this man.' 'Yes,' they answered. 'In swearing allegiance to him we are pledging ourselves to wage war against all mankind.'"
Ishaq:475 "
Allah commanded that horses should be kept for His enemy in the fight so they might vex them. We obeyed our Prophet's orders when he called us to war. When he called for violent efforts we made them. The Prophet's command is obeyed for he is truly believed. He will give us victory, glory, and a life of ease. Those who call Muhammad a liar disbelieve and go astray. They attacked our religion and would not submit."
