I was raised as a Catholic - or at least, my mom attempted to do so. I attended church at the time, and I had suspicions about some of the traditions there that seemed a wee bit gross.

Two habits, in particular, seem to give excellent opportunity for the spreading of microbes. The communion is one. It is conducted during every Catholic mass, and it involves the priest handing out small, very thin, blandly tasting slices of bread to everyone in the audience who queues to receive one. While some people take the communion into their hands, many open their mouths and accept it on their tongue. The priest might try to avoid touching people's mouths and tongues, but this is hard to achieve, so he most likely spreads microbes onto bread which ends up with other people.

The other questionable practice I recall is the font with the holy water. Whenever a believer enters or exits a Catholic church, they are expected to dip their fingers into an open bowl of water that might be changed now and then, but looks and smells fairly stale. The believer then ought to make the sign of the cross with their wet fingers, which - depending on how the person chooses to do it - involves touching the holy water on their forehead as well as possibly the lips.

The Catholic church used to have more questionable rituals yet. Nowadays, there is a part of the mass where members of the audience shake hands and extend peaceful wishes to the other random attendees around them. Centuries ago, this ritual used to involve kissing on the lips. (Genders were separated, so you would kiss people of the same sex.)

The reason I'm writing about this today, though, is not about the unhygienic rituals themselves. It's about what people's participation in, or avoidance of, these rituals, suggests about the depth of their beliefs. See this:
Catholic churches in Italy are installing automatic holy water dispensers to help reduce the risk of spreading swine flu.

The outbreak of the H1N1 virus has led many churches to suspend the tradition of having holy water in open fonts into which people dip their hands.

The new machine works like an automatic soap dispenser, squirting water when a hand is passed under the tap.

[...]

Churchgoer Marta Caimmi agreed.

"It's great," she said. "Thanks to this we are not worried about catching swine flu. It is the right thing for the times."

[...]

"Some people had stopped dipping their hand into the holy water font as they were afraid of infections," he told Reuters.

"Some people even pretended to touch the water but they just touched the marble edge of the font. I think that it is a pity to lose our traditions."
I'm pointing this out because I think it demonstrates the underlying rationality of people whose ostensible faith ought to be irrational.

The holy water in church is supposed to be part of a purification ritual. It is supposed to be holy. Blessed. Pure. Believers are supposed to spread it on their skin (or lips) to purify themselves with it.

And yet: the believers' very behavior, their very comments above, demonstrate that they are aware of how microbes can spread in stale holy water. They very much suspect that the holy water doesn't have the purification powers needed to cleanse it of microbes. They want to create the appearance of following tradition, however. It is nice to have a ritual to signal their faith, to show that they fit in.

With traditional holy water fonts, they face a dilemma. They either have to pretend to touch the water, but not touch it, and risk that people will see this. Or, they have to actually dip their fingers in, and swallow a small risk to their health in order to convincingly signal faith. This makes the situation awkward, and the arrival of hygienic dispensers makes everyone relieved. Now everyone can signal their faith without worrying.

The very presence of this new invention in a church is evidence that hardly anyone there has misconceptions about the true extent of the holy water's powers of purification.

Combine this with the casual attitude to Catholic dogma that believers in Europe tend to have, and it seems that people either go to church for main reasons other than faith - perhaps they go to see others and to be seen; or else, they compartmentalize effectively in such a way that they have strong faith where it can't obviously hurt, but they switch to evidence and reason where it matters.

Since priests are the ones buying and installing the new holy water dispensers, it seems that they are at least as pragmatic as anyone else. If they truly believed, they could just bless the holy water and say that this makes all the microbes go away. Unless they doubt their powers of blessing.

And this is all a good thing. Religion can coexist with the rational world as long as it doesn't conflict it. Religion as practiced in Europe has already adapted to a large extent. Various fundamentalisms and religiously oppressive states, however, show how things become where this hasn't happened.