Before getting into the issue of how to do kiruv. The more appropriate question is: Is there a mitzva to do kiruv? What if any is the obligation to make other Jews more observant? All the discussions I have seen recently revolve around relatively superficial issues of whether kiruv is a type of marketing. Is it honest? Is it corrupt? Does it care about the individual? Are the consequences lasting?
In other words the first concern that must be addressed is: What are the sources in Torah, halacha and seforim that talk about the issue of kiruv?
I came across an interesting site devoted to these issues Oz Nidberu. I don't know who is behind it - They seem to acknowledge all Orthodox kiruv organizations as valid. But it does address the issues. In particular they have a 7 pagd pdf by Rav Yitzchok Berkowitz just listing Hebrew sources.
Here are some of the citations in English:
Devarim(6:5): And you shall love the Lord your God with all your heart, and with all your soul, and with all your might
Rambam (Sefer HaMitzvos #3): To love G‑d…This mitzva also includes that we should seek and reach out to all men that they should serve G‑d and to believe in Him. This is to make G‑d beloved of man and that He should be thought about and praised and man should be encourged to love Him… This also includes without doubt that the heretics and fools should also be approached and encouraged to know the truth that you know. The Sifre says that loving of G‑d is to make Him beloved of mankind just as Avraham did as it says in Bereishis (12:5), “The souls which he made in Charan.” In other words just as Avraham - since he was beloved of G‑d as Yeshaya (41:8): “Avraham My beloved” - wanted to increase awareness of G‑d so he encouraged men to faith and strenghened love of G‑d. You should also love G‑d and therefore encourage men to come close to G‑d.
Chofetz Chaim: The one who truly loves Hashem calls out to those far removed, that they should believe. If we want our words should be accpted we need to bestow onto them kindness for their own needs
Chinuch(#418 Concerning the obligation to love G-d): Sifre (Devarim 33) While it is stated and you shall love, I do not know haw a man is to love G‑d, hence Scripture states, “And these words which I command you this day shall be on your heart (Devarim 6:6) for as a result of this you will “recognize” the One who soke and the world came into existene. In other words, with reflection understanding in the Torah the love of G-d settles perforce in the heart. And the Sages said (Sifre Devarim 32) that this love should impel a man to arouse people about love for Him to serve and worship Him as we find in the instance of Avraham
Seder HaYom(Seder Tisha B'av): One may judged in the World to Come if he was able to be mekarev and didnt, and if one does not have the capabilties he must find someone that does
Ohr HaChaim: The highest form of a Korban is to be mekarev rechokim
Ohr HaChaim: Hashem punishes those who turn a blind eye to rechokim
Zohar: The righteous must pursue the sinners to bring them tachas kanfie H'Shechina
