Are unbaptised Christians like de facto marriages?

Some people live together, sleep together, share finances, raise children together and do many or most of the things that married couples do (argue together, begin to look and sound like each other...), yet have not exchanged explicit public promises of commitment to one another. Their habitual actions mean that while they have never publicly made and received the promises that make a marriage (or those promises remain implicit or private), they are nonetheless acting (and are generally treated) as though they are in fact married. Hence, their relationship is a de facto marriage.

Some people repent of their sins, place their faith in Christ, love God and neighbour, participate in a Christian community and do many or most of the things that Christians do (argue together, begin to look and sound like each other...), yet have not exchanged explicit public promises of commitment with Christ. Their habitual actions mean that while they have never actually made and received the promises that make a Christian (or those promises remain implicit or private), they are nonetheless acting (and are generally treated) as though they are in fact Christian. Hence, are they de facto Christians?

Just a thought.