http://ascentofsafed.com/cgi-bin/ascent.cgi?Name=avos2Mishna 14"Rabbi Eliezer said: Be diligent in the study of Torah; know what to answer a heretic; and know before Whom you toil, and Who your employer is that will pay you the reward of your labor."One might conclude that if a person learned those parts of Torah which would provide an answer to a heretic, but he never met one to defeat, that he learned in vain. This is not so - "know before Whom you toil." G-d desires the heart of man, and He will certainly pay you your reward, just as if you had actually met a heretic and had defeated his spurious arguments.
Midrash Shmuel (3)
A hereticIt should be noted that an apikoros, who believes that the world was not created, and who denies the existence of G-d, has no rectification and elevation. The Ba'al Shem Tov taught that a gentile idol worshiper has more of a chance of being rectified than an apikoros. In the future G-d will pour out his wisdom and truth even upon the nations of the world, but not on a heretic. Their only rectification is total annihilation.
Tzemach Tzedek, Or HaTorah, NaCH, p. 782 (3)
A man once came to the Tzemach Tzedek, the third Lubavitcher Rebbe. He complained of being plagued with thoughts of doubts about the Creator. The Rebbe asked him, "Why do you care?" Surprised, the man hesitated for a moment, then replied, "Because I am a Jew." The Rebbe promptly responded, "If that be the reason, everything is fine."
"Do not consider yourself wicked"Literally, the mishnah states, "do not be wicked by yourself." One who divorces himself from the community and remains by himself is automatically considered wicked.
Rav Moshe Yechiel of Azrov (2)
"Know before whom you toil."As explained in Tanya, knowledge refers to an inner bond. Every person has the potential to develop such an inner bond with G-d. Although he labors for Him as a servant, there is nothing preventing him from establishing a deeper connection.
This also affects the nature of a person's relationship with G-d with regard to reward and punishment. Although there are many intermediaries by which G-d dispenses the reward granted for observance, a person must know "who his Employer is, and who will pay him the reward of his labor," and realize that the source for the reward is always G-d Himself and not the intermediaries.
The Lubavitcher Rebbe (1)