Kiddushin, Chapter One, Mishnah Ten
The first section of this mishnah presents a very straightforward version of rewards and punishments. Those who perform commandments are rewarded and those who do not are not rewarded. Obviously, this mishnah is expressing an ideal which often does not match reality. The problem of good people not being rewarded, or the problem of an omnipotent God in control of a random and often cruel world is called theodicy and was recognized well by the rabbis. There are many other answers in rabbinic literature to the problem of theodicy, including an extreme statement such as there is no reward in this world. Our mishnah persists with what I perceive to be a very optimistic outlook. Despite all of the evidence to the contrary the world in which we live is ordered and good. It is a reward in which the righteous receive reward and the wicked are punished.
The second half of the mishnah, the final part of the chapter, teaches that in order to be considered part of the civilized world a person must be versed in Bible, in Mishnah and participate in the ways of the world. The ways of the world probably means to have a profession although it may also mean to have polite manners.
1) He who performs one commandment is rewarded, his days are prolonged, and he inherits the land,
a) But he who does not perform one commandment, is not rewarded, his days are not prolonged, and he does not inherit the land.
2) He who is familiar with Bible, Mishnah, and the ways of the land will not easily sin, as it is said, And a threefold cord is not quickly broken (Ecclesiastes 4:12).
a) But he who is not familiar with Bible, Mishnah and the ways of the land does not belong to civilization.
Section one: The mishnahs statement sounds almost too extremeto receive reward all you have to do is perform one commandment? Therefore the Talmud interprets this to mean that a person who has half merits and half faults is rewarded for the performance of the one commandment that puts him or her over the top. Similarly, a person who has more faults than merits and does not perform more commandments in order to even things up does not receive a reward. The important thing is that since a person never knows what their status is they should treat each opportunity to perform a commandment as it that is the commandment that will put them over the top. This is an attitude to life that bequeaths importance to each of our individual choices, leaves hope for those who have led less than perfect lives and prevents haughtiness in those who believe that they have led good lives.
The peculiar language of the mishnah he who does not perform one commandment is a euphemism for he who commits one transgression.
Days are prolonged is understood to refer to a long life in this world and inherit the land is typically understood to refer to a reward in the world to come.
Section two: To be a part of civilized Jewish society one must be both learned and take part in worldly activities, namely work. Occupation with the study of both written and oral Torah, accompanied by a livelihood provides a person with a culture which will prevent him from sinning. One who is not engaged in all three is not considered to be civilized. In another words, in the eyes of the rabbis, such a person is a barbarian.