Many of us have been there before. You begin an argument with, say, a Protestant, concerning the Eucharist. You try to show him that Jesus, in John 6, reveals that we are to eat His body and drink His blood, while the Protestant attempts to prove that such verses are mere symbolism. You effectively argue from the original Greek, however, that the wording used in the verse cannot be interpreted in any way other than in a literal way.
Then it happens: the Protestant, becoming frustrated, perhaps not having a clear answer to your argument, and out of the blue throws out a statement such as, 'Well how can I take you seriously when you also believe that Mary remained a virgin her whole life? How ridiculous!'
Or how about the time when you discussed the personhood of the unborn with your pro-choice friend. You effectively used philosophy and science to show that the unborn is a living human being who has the same right to life, only to be met with a comment like, 'I cannot except the beliefs and teachings of an organization that covers up for child sexual abuse.'
These types of responses, known as red herrings, are logical fallacies that seek to distract you from the topic at-hand, like when an actual red herring throws off the scent of a dog. It is very frustrating to deal with a red herring because it causes you to dramatically switch topics despite not being provided with an adequate response to your previous engagement.
If you are ever in this situation, then I would like you to keep the following three tidbits of information in mind:
1. Do NOT engage
It can be tempting to interact with a red herring argument once it is made, since it is usually designed to put you or your beliefs in a bad light, thus causing you to play defense and address the comment.
Don't do that. All it would do is lend creedence in the mind of your opponent to his falacious form of reasoning. Rather, bring the discussion back to the orginal debate. Saying something like 'I understand that Mary's perpetual virginity is a cause for concern for you and I would love to discuss that with you in the future, but since it does not have to do with the truth or falsehood of the Eucharist, I think it would be best to continue with that conversation first' will probably be enough to bring the discourse back on point.
2. Determine if the red herring is unintentional or intentional.
For a red herring to be 'unintentional' means that the person did not mean to commit a logical fallacy; he might truly believe that it is an effective argument against your position. If you sense that this is the case, then explaining why it is a fallacy and what is wrong with arguing using fallacies like that, may prove beneficial.
For a red herring to be 'intentional' means that the person purposefully utilized the red herring; perhaps he had no response to your argument and is grasping at anything he can in an attempt to respond, or perhaps he just wanted to make you look as bad as possible. If you sense that your opponent is purposefully attacking you with a red herring, then calling him out on it is the best route to take; trying to explain what a fallacy is will not help him, because such a person usually does not care.
Learning what your opponent's intentions are for uttering the red herring will only help you to interact effectively with him and will keep the conversation moviing forward as much as possible.
3. Be willing to discuss the red herring later.
Many times the reason why somebody brings up a red herring is because they do not have an answer to your argument, but are nontheless even more bothered by some other aspect of your worldview. While we should not, as stated before, engage in that discussion immediately, we should make a mental note to discuss that at some future time.
The abortion advocate, for example, may very well have brought up the sexual abuse crisis because it is a deep concern for him. As a result, it should not be ignored. We should bring the discussion back to abortion, but we should also establish with him a desire to discuss his other concerns at some point in the near future. By doing so, you will address the red herring in a way that will hopefully be satisfactory to him, while at the same time take his struggles with the faith into consideration.
These will all be difficult to follow at times. Emotions usually run high on both sides, the giving and the receiving end of a red herring fallacy. Emotional responses can appear personal and harsh, and by their very nature, they are unexpected in the heat of a given conversation; this can cause an otherwise level-headed discussion to go sideways. But by following these basic steps the scent of the red herring will not deter you from the path of evangelization.