Ellen G. White
No one who fears God can without danger connect himself with one who fears Him not. "Can two walk together, except they be agreed?" (Amos 3:3). The happiness and prosperity of the marriage relation depend upon the unity of the parties; but between the believer and the unbeliever there is a radical difference of tastes, inclinations, and purposes. They are serving two masters, between whom there can be no concord. However pure and correct one's principles may be, the influence of an unbelieving companion will have a tendency to lead away from God. . . . {TSB 17.2}