Do I believe in Karma and Reincarnation? Yes.
Karma is a universal law. What comes around goes around, what you sow is what you reap, Cause and effect.
Reincarnation is the idea that the Soul comes back again to the physical realm or spiritual realm in order to carry the effect of Karma.
If the virtuous man who has not done any evil act in this birth suffers, this is due to some wrong act that he may have committed in his previous birth. He will have his compensation in his next birth. If the wicked man who daily does many evil actions apparently enjoys in this birth, this is due to some good Karma he must have done in his previous birth. He will have compensation in his next birth. He will suffer in the next birth. The law of compensation is inexorable and relentless. (Swami Shivananda, Practice of Karma Yoga, Divine Life Society, 1985, p. 102)
If it be that good men and good women, who receive and retain this discourse, are downtrodden, their evil destiny is the inevitable retributive result of sins committed in their past mortal lives. By virtue of their present misfortunes the reacting effects of their past will be thereby worked out, and they will be in a position to attain the Consummation of Incomparable Enlightenment (Diamond Sutra 16, emphasis mine).