The Viper Within book by Sam Mills

DISILLUSIONED WITH HIS childhood faith, Jon longs to restore that sense of belonging to something greater than himself. Enter Jeremiah, magnetic and mysterious founder of the Brotherhood of the Hebetheus. In Jon, Jeremiah finds a willing disciple for his “new” religion, and an eager participant in the Brotherhood’s daring plan: they will kidnap a classmate who Jeremiah believes is part of a terrorist cell. By foiling her plot to blow up their school, the boys of the Hebetheus will command the world’s attention, show a righteous religion as the only real tool to thwart terrorism, and become avenging heroes.
But fate and faith have a twist in store for Jon as the captive girl they call Snake causes him to confront the reflection of what he's become in her eyes. Will the appeal of a blind faith be enough to sustain Jon’s allegiance? Or will he be unable to deny the viper glimpsed within himself?