And in fairness, "someone who has seriously practiced multiple religions, and ... with a degree in religious studies" is an exceptional case in terms of both experience and expertise, and not representative of others.
You should write a book comparing your experiences. I'd be fascinated.
As you can guess, my point is that this situation occurs in many other areas too, including that of religion. And here I will speak from my experience as an Orthodox Christian: this is an extremely dangerous view. The temptation to label your brother as "not a true Christian," to see yourself as superior because you've read more books, attend more services, pray more often, etc. is very great. I'm not trying to veer into proselytization here, but rather am trying to explain at least the Orthodox response to the general argument of why all Christians aren't obviously great people. :)
When it comes down to it, every person -- Christian or not, Orthodox or not -- is engaged in a very great struggle in their hearts. They have been wounded deeply by this world, even if they live in relative comfort and ease compared to another human in a worse situation. Some have chosen a particular hospital to recover in, but unfortunately struggle greatly with their illness.
I know that my own case, of having experienced multiple religions and chosen an education in religious studies, is rare. But what I am trying to say is that people being sincere about their religion takes many forms, and is more complex than a one-dimensional scale. There are indeed beacons in the Church: the saints, such as Saints Porphryrios and Paisios, who are not far from us but reposed in the 90s. But as Saint Porphyrios said, there are untold numbers of "hidden saints," who lived lives of obscurity and humility and love, not writing tracts of theology, but who lived theology, who lived communion with God.
I think that perhaps we expect a saint to be a certain kind of mythical person and we hold religious people to that kind of standard. I know that it must be disappointing when you meet a Christian and do not encounter faith, hope, and love. But the story of each Christian's life is not over until death -- and even at that point there is mercy.
When I was a Buddhist, many of my fellow Buddhists took great pains to emulate the Buddha. It was also important to study the teachings of a particular sect, if one belonged to once, such as Dogen in Soto Zen. In fact, the master-disciple relationship is incredibly important in some forms of Buddhism, with the master ultimately deriving his authority from his lineage, which is rooted in a founder.
I think it would be difficult for Christians, whose name essentially means "Christ-like", to not consider what the founder of their religion would do. Perhaps it's not as big of a movement anymore, but there was a "What Would Jesus Do?" movement in Protestantism that wore bracelets bearing WWJD, to remind themselves to act in a Christ-like manner. As an Orthodox Christian, the goal of theosis is inextricably entwined with behaving like Christ.
I am sorry for downvoting you, but as someone who has seriously practiced multiple religions, and as someone with a degree in religious studies, I think that saying that founders' actions don't influence their followers is quite difficult to swallow (note: I'm making no specific statement about Islam, but rather only trying to clarify this particular point).