Like most human beings, strongly religious people tend to react with a tit-for-tat attitude towards callous and derisive insults hurled at what is important to them. We are, though, under obligation (and not merely Christians, but most major faith traditions) to behave towards you as we would wish you to behave toward us, no matter how strong the provocation. But that’s fighting a human instinct (or at minimum social conditioning), as I’m sure you’re aware.
You are correct, though: nobody would easily mistake your behavior towards anyone with religious faith for respect.
With regard to the broader issue, let’s place a little context. First, social custom (“etiquette” in the anthropological sense) is a strong bonding mechanism. If it is your wish to be accepted as a part of the group by a tribe which rubs blue mud in their navels, then you are wise to rub blue mud in your navel. (Whether this is a good idea in a broader context is moot: the issue is, “when in Rome, do as the Romans do.”)
To quote a rather unusual ad campaign I saw a while ago, “If you knew for a fact that Jesus Christ was going to show up, flesh and blood, at the church down the street next Sunday, wouldn’t you try to be there and see Him? Well, [picture of Host and chalice here], He is!” The doctrinal beliefs of churches professing the Real Presence is that Jesus becomes present, by a miracle of the Holy Spirit, at the consecration of the communion elements, under the forms of bread and wine. The accuracy of that belief too is moot; we are exploring their social behavior.
Now, if in fact Jesus is one’s Lord and Savior, and He is present in the Eucharistic elements, then those elements become deserving of utmost respect, because in point of fact (or rather of firm belief), they are in fact His Body and Blood. This has led to some rather extreme practices among some devotees of Eucharistic adoration. But at absolute minimum, one must understand the consecrated bread and wine to be deserving of respect as things set apart as holy. Even persons who do not share such beliefs would normally treat them with respect out of courtesy for the beliefs of those who do.
Hence, up until the 1970s, Western churches which professed belief in the Real Presence tended to require kneeling communion of their members, as a mark of such respect. (Ybeayf can fill us in on Orthodox practice if he chooses.) The more modern trend is to receive communion standing, respectfully, hearkening back to the practices of the early church and emphasizing the forgiven, sanctified nature of the members, in contrast to the contrite humility underlying the kneeling.
As Tom~ notes, the Catholic custom is to enforce a particular mode of practice by canon law. In my own Episcopal parish, one may receive standing or kneeling, and provision for communicating people preferring each is made by the ministers of the communion.