The other day, while in the beit midrash, I overheard a high school student ask his rebbe, "If you had a person from Amalek in front of you, would you kill him?" [For background on Amalek, see Deuteronomy, the end of Chapter 25.]
The rebbe dodged the question in favor of getting to the topic at hand in his shiur, but he suggested that the student ask me. The student hasn't yet come to me, but I do have my answer ready.
I think it's a good question. I think we should overlook the fact that this mitzvah is not real today - that Amalek may well be ideological, that we don't know who Amalek is, and so on. Yes, eradicating Amalek is not a situation we face. But the point of his question is not this mitzvah, per se; rather, the question is how far you would go in violation of human instinct and social norms to fulfill a mitzvah.
Rabbi, you are horrified by the barbaric murder of a British soldier in London. So, Rabbi, what would you do if you believed that Judaism required you to execute someone?
And my answer is that this hypothetical mitzvah would pose a challenge to my emunah [faith], as do many mitzvot; the difference is simply in degree.
To be clear: It's not about agreeing or disagreeing with a particular mitzvah; I take it as a given that killing people who do not pose any clear threat is something we disagree with. Rather, it's about overall faith in Judaism, and the strength of that faith.
Many (most?) of us who lay claim to belief still live with questions regarding Judaism. We have questions about Gd's actions in the world, the authenticity of our tradition, and so on. The degree to which faith overcomes doubt is the degree to which faith can motivate us to follow Judaism even when our native instincts, or social instruction, would lead us elsewhere.
There are Jews whose faith is strong enough to get them to support Jewish causes with their money, but not enough to get them to run their lives by Judaism's principles.
Some people's emunah is strong enough to lead them to observe Shabbos, or kashrus, but not to "come out" as Jews at work or in a social setting.
Some people's emunah is strong enough for all of these – but they stop short on something more demanding, or more challenging of their belief.
And for many (most?) of us, I expect, emunah would fall short of convincing us to execute an Amalekite who did not appear to pose a threat.
But enough of my response- What would you say to that high school student's question?