Effortlessness means not doing anything, inactivity - AKARMA. Effort means doing much, activity - KARMA. Both have to be there. Do much, but don`t be a doer - then you achieve both. Move in the world, but don`t be a part of it. Live in the world, but don`t let the world live in you. Then the contradiction has been absorbed. Then you are not rejecting anything, not denying anything. Then the whole God has been accepted.
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
All major religious traditions carry basically the same message, that is love, compassion and forgiveness the important thing is they should be part of our daily lives.