At Sukkot services on Monday I heard a teaching I liked, and I forgot to include it in my earlier Sukkot post. I heard this from Rabbi Yisroel Altein, who taught it in the name of the last Lubavhicer rebbe.
On Sukkot we take up the "four species"; this is one of the obligatory mitzvot of the holiday. The rabbis (I'm not sure where and he didn't say) compare the four species to four types of Jews:
The etrog (this is a citrus fruit) has both good taste and good fragrance; this is like a Jew who both has learning and performs mitzvot.
The myrtle has fragrance but is inedible and the palm is edible but has no fragrance. One of these represents a Jew with learning but no mitzvot, and one represents a Jew with mitzvot but no learning (one who does the mitzvot because he's been instructed to, but lacks deeper torah knowledge).
The willow has neither fragrance nor taste, and represents a Jew with neither learning nor mitzvot.
But, the rabbi said, just as you can only perform the Sukkot mitzvah if you have all four -- if you're missing one of them it's not kosher -- we as a community aren't complete if we don't include all four types of Jews. Not, heaven forbid, that we should encourage people to stop learning or doing mitzvot but, rather, that there are people with neither, and they are still Jews and deserving of being included in the community.