(2Co 6:14) “Be ye not unequally yoked together with unbelievers: for what fellowship hath righteousness with unrighteousness? and what communion hath light with darkness?” The person of the lost is twofold: body and spirit. The person of the saved is threefold: body, soul, and spirit. The lost and the saved can only fellowship on the level of the flesh and old fallen nature. Since we still live and battle the flesh, such a yoke makes living for the glory of God much harder.