Do not be mismatched with unbelievers. For what partnership is there between righteousness and lawlessness? Or what fellowship is there between light and darkness?
The passage in 2 Corinthians from 6:14 through 7:1 is slightly set apart in most study Bibles, indicating that it seems to be a fragment from another letter altogether. (Notice how logically the message flows from 6:13 to 7:2.) So it's impossible to know exactly what question or issue Paul may have been addressing in this passage. At the deeper, metaphysical level at which scripture truly speaks to us, however, the guidance not to be "mismatched with unbelievers" is a clear affirmation of spiritual law. '”Being matched” is more than just “being friends with” (or “being married to,” for that matter). Jesus tells us to love unconditionally, and he set a powerful example in his willingness to teach, heal, share and socialize with people of all beliefs.
What we are warned against here, I think, is any tendency to compromise or dilute our own spiritual understanding and empowerment for the sake of getting along with others. We don't try to impose our beliefs on others whose beliefs are different, and we don't judge them negatively for the beliefs they hold. But it's essential that we lovingly hold firm to our own spiritual understanding. The Christ Presence within us is an energy of infinite love and appreciation that can bless friendships and relationships of all sorts. But we cannot be willing to dilute our commitment to that Christ Presence. We surrender completely to the Christ, and allow that energy of divine love to guide all our interactions with others.