Scandals don't disprove Christianity
even when they occur at the highest levels. Recently there has been much made of a prominent layman whose past indiscretions were trumpeted by a liberal catholic newspaper, as if this sin discredited whatever other work the man has done.
But sin would only disprove Christianity if Christians taught that baptism made one instantly perfect. But that isn't the case. Authentic Christianity teaches that all are sinners, and sin in Christians doesn't contradict that teaching.
Rather, as Chesterton pointed out somewhere, the continuance of evil in human affairs despite the attempts of secular social reformers to eradicate it is much more of an argument against them than against Christians.