From the scientific view, the theory of karma may be a metaphysical assumption -- but it is no more so than the assumption that all of life is material and originated out of pure chance
To find Buddha, you have to see your nature. Whoever sees his nature is a Buddha. If you don't see your nature, invoking buddhas, reciting sutras, making offerings, and keeping precepts are all useless. Invoking buddhas results in good karma, reciting sutras results in a good memory, keeping precepts results in good rebirth, and making offerings results in future blessings-but no Buddha.