Does being unequally yoked apply to more than marriage?
Yes. Being unequally yoked extends beyond marriage to business and any situation where two or more people must work for a common cause. Righteousness and unrighteousness, light and darkness, are distinct opposites; they cannot cohabit, and unequal yokes are beaten from day one.
Les teaches that being unequally yoked does not stop with marriage. It can apply in business or anything wherever two people, or however many, have to work for a common cause. He points out that people do not change except for what salvation does, so starting with an unequal yoke means you're beat from day one. He illustrates with a Colorado realtor's rule of thumb about paying too much per cow-calf pair: you're beaten before you start. The passage then asks what fellowship righteousness has with unrighteousness, what communion light has with darkness, and what concord Christ has with Belial—two distinct opposites that will not cohabit.