I think religious people probably do adhere to genuine beliefs and resist temptation more reliably than the general population, but it's easier to perceive the opposite because:

1. Those circumstances stand out more because the stark hypocrisy highlights the case as more significant. Teachers are one of the most likely demographic to commit sexual assault on a child, yet when a priest does it, even if it happens only a handful of times, it stands out as far more significant, even if it's less representative. (and every instance is an abominable tragedy)
2. While genuine belief confers stronger resistance to temptation, religious prevelence creates other cultural impacts that create incentives for those with disengeuous belief. If a republican candidate can make career strides by advocating traditional marriage and sexuality, then why not appeal to a Christian voter base while getting some action at the gay bar on the side?