Explain unequally yoked together?

2 Cor 6:14
Be ye not unequally yoked together with unbelievers: for
    what fellowship hath righteousness with unrighteousness? and
    what communion hath light with darkness?

Yoked, bound together...Oxen were placed together with a wooden yoke so they could pull together a heavy plow. If one was weak or wanted to go another direction, the work could not be accomplished.   People who come together to work together, in a marriage or in a partnership, must be of the same mind, the same spirit and be going the same direction.   Someone loving the Lord, in the light and serving him, is not to be in partnership with a non believer, or a devil who is heading for the darkness and the things God hates.   Gary