1. Don't do this: Create a "straw man" (or in this case, a stick man) argument that makes your criticism seem almost gratuitous. If your opponent is as stupid as you seem to think, then why are you debating with him in the first place? It is a little bit like beating up your grandmother and then patting yourself on the back for it.
Instead, maybe try this: If your opponent's position is worthy of debate, then first present their argument as they themselves might present it, not as the most the ignorant clueless person on earth might envision it. This is what we call the "benefit of the doubt", something I know that you would not deprive of those with whom you are debating. To do otherwise makes it look like as if you are not so much trying to make a good intellectual argument as trying to bully someone into agreeing with you. And being someone who is trying to give you the benefit of the doubt, I am going to assume that's not what you're doing.
Instead, maybe try this: Ask the other individual why the Church was involving herself so heavily in the conclusions of science, as opposed to focusing on theology. Then ask them why the pope chose to act more like a political animal than the vicar of Christ when pursuing Galileo. These are real questions to be asked, questions that provoke real discussion.
Instead, maybe try this: Keep your arguments current! If a joke falls in the forest and no on gets it, is it still a joke? Well, when it comes to a real debate, the answer is no. There may have been a time when this was an appropriate critique, but we do not live in those times anymore, so stop making it.
4. Don't do this: Claim that Hitler was a Catholic and therefore motivated somehow by this to exterminate the Jews. Minimal research will uncover that Hitler disdained Christianity, mainly because its central teaching demands care for the weak and most vulnerable, a virtue (or vice from his perspective) that he thought deplorable. Hitler was baptized, yes, but repudiated his faith early on in favor of a mythology about the Aryan race. The only hint of religion in the Nazi ideology was the Swastika, which was lifted from the Hindu religion.
Instead, maybe try this: I agree that Christianity espouses things that are undoubtedly good and worthwhile. But if it's as good as you claim, then why do so many Christians fall short of those standards? Or, given what was happening to the Jews during WWII, why didn't more Christians step up to the plate and help them? I mean, even Gandhi was quoted as saying in essence that he liked Christ, it was "Christians" that he had a problem with...
Instead, maybe try this: Perhaps a better path to take for the one who rejects the golden rule of medical ethics (i.e. the end doesn't justify the means), is to say that out of compassion we must do all we can to mitigate human suffering. There are all of these embryos out there that won't be used anyway, so why not commit them to research. Of course, this is merely an argument from emotion and not based on consistent medical logic, but its better than the one he's got going. Incidentally, the Church doesn't call things like embryonic research heresy. Immoral yes, but heresy refers more to her dogmatic declarations (viz. Jesus is the Incarnate God)
Instead, maybe try this: Although each parent wishes to instill in his or her child the best of what they have, at a certain point a child must own their beliefs. Consequently, no individual should choose to devote their lives to a set of values without thinking about them critically first. In other words, you should know, at least to some extent, the intellectual reasons for believing the things that you believe. Otherwise you may indeed be a mindless zombie who accepts a mindless anti-tradition like the one so eloquently articulated in this comic.
7. Don't do this: Cite dietary restrictions in the Old Testament as proof that Christians are hypocrites. Towards the end of this particular "comic" tract the author suggests that it is silly to take a cartoon seriously. I am not really sure why a cartoon makes such insults more trivial; it certainly makes what the author is lampooning seem more trivial, but not the cartoon itself. For example, if I wrote a cartoon mocking someone's mother and then said afterwards "Lol" or "JK," I don't think that that would mitigate my insulting behavior (and rightly so). However, I will agree in this one sense: I find the religion that he has so cleverly invented for Christians as absurd as he does. Fortunately, whatever religion he is referring to is not one that I subscribe to either. Christians believe that the law of the Old Testament is fulfilled in Christ; that is to say that no food is unclean (which thankfully includes those delectable little pigs). If this were not the case, then why not cart out circumcision as even greater evidence that all Christians are a bunch of hypocrites? I would have to say that even his beloved "Dark Lord Fire Ape" would have to agree with me on this one.
Instead, maybe try this: Focus on the New Testament, because if you are really going to undercut Christians, it is not going to be by pointing to some inscrutable act in the Old Testament (which the Church has always said is superseded, or fulfilled, in the New Testament). If it were me, I would go after the fact that Scripture doesn't overtly denounce slavery. Or maybe I would bring up the fact that women seem to be "kept in their place" in some of Paul's writings- and as important as women were in the early Church, none were given a place in the hierarchy. These criticism are nothing new either, but at least they are not so easily swatted away.
Instead, maybe try this: It is understandable that some want to set boundaries regarding sex. I mean if we were all to go around doing whatever we felt like, what kind of society would that be? Even so, when setting such restrictions we should be careful not to imply that sex is something loathsome, or something that we should associate with being impure. In the past, there have been people from various religious sects that do go to this extreme, and do purposely encourage this negative association. Would that they would stop this! We know that boundaries are what separate us from the animals, but nevertheless, we should still engage in a real and honest debate about what those boundaries should be. In other words, what justification does Christianity (and other groups) have for so rigidly drawing the boundaries of sex at heterosexual marriage?
9. Don't do this: Bring up some scandal in the history of the Church when you know nothing about it. I cannot tell you how many times I have heard someone throw out in a discussion- unrelated to anything you were previously talking about- some horrible scandal associated with the Church. You could be talking about the pope meeting Netanyahu in Jerusalem, and someone will say out of no where; "What about the Spanish Inquisition?" If someone wants to criticize the Church, great, just make sure your criticism actually relates to something in the conversation, otherwise it can look as if you are just trying to pull anything out of the air to make the Church look bad. Secondly, know something about the thing that you are criticizing. Reciting the words; "What about the Inquisition?", or "What's up with the Crusades?", is not equivalent to an argument. Oftentimes, all I really need to say in response to someone like this is; "What about it?" and that pretty much ends the conversation. The truth is these individuals generally know very little beyond what has been repeated to them- which consists mainly of: the Church did this, and it was bad because bad things happened. There is plenty to criticize, but to have only the most superficial understanding of what you are so profoundly against is unacceptable by any standard.
Instead, maybe try this: How can a Church which claims to want to treat every human being with the utmost respect and dignity hand them over to be tortured. How can a Church so dedicated to the family allow some of her leaders to abuse children? How can Christians who claim to love their neighbor as themselves look the other way when Jews are being slaughtered in concentration camps? All of these are real questions, which require real answers. Nevertheless, I should say that even while you criticize the Church by holding her to these high and worthy standards, you must also recognize that the mete by which you measure her is the standard that she herself established in the first place. And furthermore, when you do critique her, don't pretend that the world would somehow be immaculate and sinless without the Church. You also might want to avoid behaving like you yourself are the arbiter of all that is good and right and just in the world. Why do I say this? Because sometimes critics and historians have the hubris to pretend that they would have been above the fray had they lived in those former times.
10. Don't do this: Lump all religious ideologies into the same group. I know this makes your criticism of religion easier, but it doesn't do justice (if you are in fact concerned about that) to the wide-ranging set of beliefs. There is no idea that is more powerful than God. Therefore, it is not surprising that some will use this powerful idea for nefarious purposes. One might view God as an energy, another as a Force, another as the State, another as themselves, and another as chaos and death. The question is not whether you believe in something all-powerful; the question is what you believe to be all-powerful. The next question you should ask is whether that belief actually contributes to a society governed by virtue, or one that is rife with vice.
Instead, maybe try this: Not all religions are created equal. Plain reason tells you that there are some ideologies that are wicked (whether religious or secular), and some that seem to operate on more humane principles. What you need to look at in order to gauge this are three things; a) what the core values of that ideology are; b) what its role in history is; c) how its adherents behave. Implying that every religion/ideology is ignorant simply because it is religious, is not only terrible logic, but it fails in a very basic sense to understand what motivates and inspires human beings to act. Whatever a man values in this life is the barometer for how he behaves.
Instead, maybe try this: "Since I believe that man is a big bag of meat, then I will be consistent with my views and say that life is meaningless and that it doesn't matter what you do. There is no truth, nor are there any ethics to contend with." If these are in fact your views, then go forth, my budding atheist, and define yourself as it pleases you. Then sail off into that sunset of oblivion where everyone, as you recommended in your cartoon, keeps their religion to themselves... except you.
If you wish to see the cartoon, you can view it by going to the link below. But be forewarned, it may be highly offensive to anyone who reveres God, or holds religion in high regard: