Is it obligatory to renew the marriages of those who converted from disbelief?

Question:
The first message in this episode is from a listener (M. K. A.) from Khartoum, Sudan. He says: I am from a family whose grandparents were not Muslim; rather, they worshipped idols. My father married in accordance with that, not according to the Book of Allah and the Sunnah of His Messenger (peace and blessings be upon him), and we were born. However, by good fortune, we grew up in a Muslim environment. I attended school among Muslim students and teachers, and from a young age, I learned in school to read the Qur'an and perform the prayer, although there was some negligence regarding the prayers at times. But in the end, my Lord guided me, and I have adhered to the Sunnah of our Prophet Muhammad (peace and blessings be upon him) for several years, and praise be to Allah.
My question is: Is my Islam correct? This is because I practiced some of the rituals and customs of my ancestors, but that was only out of curiosity and due to my ignorance of their prohibition. Also, my father was not Muslim. My father now prays and fasts, and he has abandoned the non-Islamic customs and rituals. He did this without any preliminary steps, such as publicly declaring his Islam, because he had been living among Muslims for a long time, but he was practicing non-Islamic rituals. At the same time, he was praying and fasting. But in the end, he abandoned the non-Islamic rituals and began praying, fasting, and other Islamic rites. Is his Islam correct despite his not publicly declaring it and not performing the specific bath for entering Islam?
What is required of my father regarding his previous marriage, which was without Islam and not according to the Sunnah of the Prophet (peace and blessings be upon him)?
Please guide us in these matters.
May Allah reward you with good.

Answer:
Praise be to Allah. As long as repentance and returning to Allah have occurred, and you and your father have become upright, then praise be to Allah.
As for the past marriages, they are not looked into; because they were according to their way. When disbelievers convert to Islam, their marriages are confirmed. Therefore, it is not necessary to look into that, but rather one should look at the present time. If the believer repents, and the man repents from the rituals or deeds he has that contradict the Shari'ah, that is sufficient, and praise be to Allah.
So you must adhere to repentance, and your father must adhere to repentance. As long as the wife is righteous, and is not his sister or his aunt, but rather there may be some defect in some of the rituals among them, the ruling in that is that it is confirmed as it is, like the marriages of other disbelievers, and it is not looked into after that. They are confirmed in their Islam and in their marriages, just as the Prophet (peace and blessings be upon him) confirmed the marriages of those who converted on the Day of the Conquest and others, and he did not change them. But if it were to be revealed to him that he married his sister through breastfeeding, or his aunt through breastfeeding, or his brother's daughter through breastfeeding, then he must separate from her after his conversion to Islam; because the impediment exists.
As for if the defect is in something in the contract, such as the absence of a guardian, or something similar, then they are confirmed in their marriages. Yes.

The presenter: May Allah reward you with good. What about the bath, Your Eminence? He says: His father did not take a bath when he entered Islam?

The Shaykh: The bath is a recommended practice (sunnah), and it is not obligatory.

The presenter: And it is not obligatory?

The Shaykh: Yes.

The presenter: So there is nothing required of him?

The Shaykh: There is nothing required of him. Yes.

The presenter: May Allah reward you, and may Allah reward you with good.