A friend of mine died. His adult son opened a charge card without his notice till they missed a payment. Is the estate responsible to pay a charge card that was never his to begin with?

A friend of mine died. His son opened a credit card without his knowledge and now the credit card co. wants his estate to pay. This was NOT his debt and he did NOT open this account. His son had stopped paying on the account and found the person before he died. Is his estate responsible for any of this debt?

Probably not.

By the way, you don't need to ask the same question repeatedly. Someone will get to you in due course.

Anyway, as I understand your question, the decedent (your friend) never authorized nor was aware of the credit card account opened in his name by his son.

Did this happen before the decedent died? You say that "His son had stopped paying on the account and found the person before he died", but that part is confusing. The son found what person?

Did the decedent benefit in any way from the charges incurred on the credit card?

It can't be your estate. You have not died (or at least had not died when you posted your question :)). It would be your friend's estate.