Paul gives direct teaching on the subject. He says (II Cor. 6:14), "Be ye not unequally yoked together with unbelievers," etc. In the case of the Corinthians, such a union must have been exceedingly uncongenial, as the unbeliever was usually an idolater. The disparity is not so marked in our day, but it is sufficient still to produce a lack of real harmony. Religion should be to the Christian the first and fundamental element of life. To have a partner who has no sympathy with it is to raise a barrier between the two which keeps them separate in the highest and holiest spheres of life. Generally it leads to the Christian forsaking his faith.