Is it permissible to marry a Christian divorcee who committed adultery after the divorce, and when is that possible?

It is not permissible to marry any woman except with a valid Islamic contract that fulfills all pillars and conditions. If the marriage to the aforementioned woman is through an invalid contract, it is null and void, and cohabiting with her would be fornication. A civil contract, as a man-made system, is not considered valid for marriage in Islam. It is also a condition for marrying a woman from the People of the Book that she be chaste (muhsana), and it is not permissible to marry an unchaste woman. Most women in the West are unchaste, or their Christianity is merely a name. Repentance to Allah is obligatory, and it is not permissible to marry her due to her lack of chastity. Allah, the Exalted, says: "The fornicator does not marry except a [female] fornicator or polytheist, and forbidden to the believers is that." (Surat An-Nur, 24:3). A Muslim should marry a Muslim woman.