In attacks on the theory of memes, the most common argument is the "Chinese telephone scenario" in which a line of people are given a statement and asked to pass it along the line. By the end of the line, the message is completely garbled--suggested proof that there can be such thing as a meme because memes do not transmit with any fidelity.
But a simple declarative statement is not analogous to a virus, it is analogous to a single strand of DNA. Viruses are not just free floating strands of DNA. They are single celled organisms, barely viable without the medium of other cells which they hijack and use to reproduce themselves. But they are, themselves, very simple cells. A meme would have to be a package. That package could contain multiple ideas, but the meme itself would be the delivery system.
What would such a delivery system look like, when the target is a human mind?
In A Devil's Chaplain, Richard Dawkins mentions a girl who had, via her parents, assimilated the mannerisms of Ludwig Wittgenstein. We are all composites of the people we admire. Earlier generations emulate their heroes, and we emulate them, and so on. The dead live on through us--but the dead are not the only ones that we take into ourselves. Living friends, and imaginary friends, become part of us. Even the characters of fiction become advisors, personalities who take on a new life in our imaginations. Like Woody Allen's character in Zelig, we take on the mannerisms and opinions of those around us, particularly those we love.
A meme is not a simple disconnected idea. Like the person it infects, a meme has a mind, a set of attitudes, behaviours, and beliefs. Memes are not simple ideas; they must be formed as characters, thumbnail sketches of personalities. They are living things that nonetheless only fully come to life by being hosted by others. The mechanism itself is usually positive. We emulate what we admire. The trick, in perpetuating a meme, is to get the person to admire someone. Once that is done, the adopted hero enters the mind of the converted, carrying along whatever ideas are associated with that character.
This is the job of religious proselytizers--to sell you the character. Once they have done that, they can fill in the detail of the character, by telling you stories about what the character did and said. The character becomes a permanent fixture of you mental landscape. The question "What would Jesus do?" is a hallmark of this process. Christians keep the character of Jesus in their heads, where he becomes a living continual companion. But the personality of that character is determined by the sect you belong to.
There is still a problem of fidelity, but the name of the character is usually assumed by each devotee to represent the same conception, and so a broad based alliance can be formed if fellow believers do not inquire too deeply. Fidelity within each sect is enforced by orthodoxy, a constant reiteration of what that character approves and disdains. Acceptance of the central figure facilitates an open door to personal attitudes, as the central figure can be 'reprogrammed' at will. As such, the religious memetic virus is a trojan, a back door into the mind of the believer, breaching personal judgement to permit external access to personal beliefs without challenge.
All widely successful religions are essentially cults of personality; at the center is a single authoritative figure who expresses the fundamental tenants of the cult; Jesus in Christianity, Mohammend in Islam, Yawheh in Judaism, the Bhuddha in Bhuddaism, and so on. Religions without a central figure survive more by tradition or individual choice than conversion. Their memetic potential is quite limited.