What the Gedolim of our times said:

The Chazon Ish Ztz"l

What do the Seforim Hakdoshim write:

• Zohar Hakodosh: The righteous must pursue the sinners to bring them tachas kanfie H'Shechinah

• Ohr Hachaim Hakodosh: Hashem punishes those who turn a blind eye to rechokim

• Sefer 'Seder HaYom': 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

• Chofetz Chaim ztz"l: 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 thier own needs
  

• A comprehensive list of marie mekomos that delves into the sugya of the Chiyuv of Kiruv, by Rav Yitzchak Berkovits
  

• Zohar Hakodosh: They are elevated three aliyos higher than any other person

• Ohr Hachaim Hakodosh: The highest form of a Korban is to be mekarev rechokim

• If people would know the greatness and the reward of kiruv they would chase after it (Ohr Hayoshor)

The Matzav of Klal Yisroel and why we need to act fast!

• The Vanishing American Jew by Rabbi Berel Wein

• A Holocaust in America by Rabbi Ephraim Buchwald
  

• The Situation is Desperate! Rabbi Jonathan Rosenblum

• The Future of Judaism by Daniel Pipes