Is a marriage considered valid if it took place between a Muslim man and an adult, independent Christian woman, and the صيغة الإيجاب والقبول (formula of offer and acceptance) was recited without mentioning the mahr (dower) at that time, then a sum of money was paid to her later, and without witnesses or a guardian (wali)? Knowing that a divorce subsequently occurred due to fear of the marriage not being valid, is it obligatory to perform the marriage contract again in the presence of witnesses and a guardian?

It is not permissible for a man to marry a woman without the permission of her guardian, whether she is a virgin or previously married. This is based on the Almighty's saying: ﴿So do not prevent them from marrying their husbands﴾, and the Prophet's (peace be upon him) saying: "There is no marriage except with a guardian," and "Any woman who marries without the permission of her guardian, her marriage is invalid."

If the guardian prevents the woman from marrying without a legitimate Islamic reason, the guardianship transfers to the next closest guardian. If all guardians prevent her without a legitimate Islamic reason, then the ruler is the guardian of those who have no guardian.

If there is no guardian or ruler, then a man who has authority in her locality, such as the village elder or the governor of the state, marries her. If none is found, she should appoint a trustworthy Muslim man to marry her. Two Muslim, adult, sane men must witness the contract.