Why did Calvinism grow so rapidly?

Calvinism was able to grow so rapidly for three reasons:

1.      Calvin’s theology was a complete, (almost) fully worked-out system which could fully take the place of Roman theology

2.      Calvinists embraced an active missionary style (or zeal, even) of the type presented by the early Church

3.      The founding of the Geneva Academy, from which many Calvinist leaders sprung

jewish people, gypsies, and political opponents.