Jews believe in an innate יצר הרע (yetzer hara) or evil inclination that entices us to stray from God.
In either case, sin is Evil with a capital “E” and denotes a rupture in our relationship with God. Certain things are sinful because they violate God’s commandments. They are sinful because God has ordained it so.
Buddhism has no concept equivalent to that of sin. While there may be gods in Buddhism, there is no God, The Eternal Creator and Judge. In Buddhism actions are judged by their utilitarian value: whether they lead to greater happiness for the person and affected others, and whether they lead to better karma, rebirth, and progress on the path to Enlightenment. The Buddhist terms for judging whether actions have a felicitous or unfelicitious effect are (in the Pali language) kusala and akusala, which usually gets translated as either wholesome and unwholesome, or skillful and unskillful. The utilitarian nature of these concepts is made clear in the Kusala Sutta (Anguttara Nikaya 2.19):
“Abandon what is unskillful, monks. It is possible to abandon what is unskillful. If it were not possible to abandon what is unskillful, I would not say to you, ‘Abandon what is unskillful.’ But because it is possible to abandon what is unskillful, I say to you, ‘Abandon what is unskillful.’ If this abandoning of what is unskillful were conducive to harm and pain, I would not say to you, ‘Abandon what is unskillful.’ But because this abandoning of what is unskillful is conducive to benefit and pleasure, I say to you, ‘Abandon what is unskillful.’
“Develop what is skillful, monks. It is possible to develop what is skillful. If it were not possible to develop what is skillful, I would not say to you, ‘Develop what is skillful.’ But because it is possible to develop what is skillful, I say to you, ‘Develop what is skillful.’ If this development of what is skillful were conducive to harm and pain, I would not say to you, ‘Develop what is skillful.’ But because this development of what is skillful is conducive to benefit and pleasure, I say to you, ‘Develop what is skillful.’”
–Kusala Sutta 
When we say that skillful actions promote happiness, we are not just talking about the happiness of the individual. In Buddhism the individual and others in the community have equal claims to happiness. Buddhism is, as Shohaku Okumura has observed,  neither individualist nor collectivist, but represents a middle-way between these dialectical opposites. This is, in part, a consequence of the Buddhist emphasis on emptiness, the interdependence of all things. It is also due to the Buddhist view of the absolute truth of the oneness of all things balanced against the relative truth of our individual uniqueness. Skillful actions promote the happiness of the individual and the community synchronistically.
Just as something unskilful, like an addictive behavior, brings ruin to the individual and his family and involves broader social costs, skillful actions bring happiness to the individual, his social group, and the larger social order. Selfish behavior does not bring genuine happiness, but only fleeting sense pleasures and ego gratification. Selfishness disturbs our loving social ties with others, creates dissension in the community, and makes us slaves to the hedonic treadmill of transient pleasure. The Buddha (like Aristotle in his Nichomachean Ethics) believed that real happiness came from the cultivation of wisdom and character. Aristotle differentiated eudamonia, or genuine well-being, from hedonia, or sense-based pleasure. Contemporary Positive Psychology is demonstrating the truth of the Aristotelian-Buddhist idea of a deeper, more worthwhile sense of well-being that is wisdom and character based.
Not only can actions be unskillful, but thoughts, which are really interiorized actions, can also be unskillful. Thoughts are often the first stirrings of action, with skillful thoughts leading to skillful actions, unskillful thoughts to unskillful ones. We are what we think. If we are to live skillfully we must first establish some degree of control over our unruly minds. This is where mindfulness comes in. If we’re heedless of thoughts we’re driven by them like a leaves in the wind. If we’re mindful of thoughts, we can exercise discerning judgment about them. We can discern whether or not a thought is skillful and then decide whether or not to rehearse, practice, nurture, and reinforce it.
Thinking about actions as being unskillful rather than sinful allows us to take responsibility for behavior without the added burden of surplus guilt. We avoid unskillful behavior because we want ourselves and others to be happy, not because we’re afraid of Hellfire or God’s wrath. The only source of retribution we really need worry about is the one we ought to: Cause-and-Effect. This is true whether one believes in the Buddhist concept of karma, or the modern scientific understanding of cause and effect.
Go and sin no more.