They lived under Communist rule and did not know anything about praying and fasting; do they have to make it up?

Firstly: 

We praise Allah for saving you from unjust and oppressive communist rule after it suppressed the Muslims for more than forty years, during which mosques were destroyed and some were turned into museums, Islamic schools were abolished and they strove to change Muslim names and wipe out Muslim identity. 

“but Allâh will not allow except that His Light should be perfected even though the Kâfirûn (disbelievers) hate (it)” [al-Tawbah 9:32 – interpretation of the meaning]. 

Communist rule, with its tyranny and oppression, ended in 1989, to the great joy of the Muslims, who went back to their ancient mosques, which they refurbished and renovated. They went back to teaching their children Qur’aan and the hijab of Muslim women appeared again in the streets. We ask Allah to bring the Muslims back to their religion in the best way and to support them and grant them victory and defeat their enemies. 

Secondly: 

A generation of Muslims grew up in Bulgaria under the oppression of Communist rule and they did not know anything about Islam apart from the fact that they were Muslims. The communist regime prevented them from learning Islam and even banned the import of the Holy Qur’aan and Islamic books into Bulgaria. 

Those who did not know anything about the rulings of Islam and Islamic worship and other duties are not obliged to make up any of those acts of worship. If the Muslim was not able to acquire Islamic knowledge and the rulings of sharee‘ah did not reach him, then he is not obliged to do anything because Allah, may He be exalted, says (interpretation of the meaning):

“Allâh burdens not a person beyond his scope”

[al-Baqarah 2:286]. 

Shaykh al-Islam Ibn Taymiyah (may Allah have mercy on him) said: 

There is no difference of opinion among the Muslims that if a person was living in dar al-kufr (non-Muslim lands) and he believed but he was unable to migrate (to a Muslim land), he is not obliged to observe Islamic rituals and laws that he is unable to; rather he is only obliged to do what he is able to. The same applies to matters concerning which he did not know the rulings. If he did not know that prayer was obligatory for him and he did not pray for a while, he does not have to make up those prayers according to the more correct of the two scholarly opinions. This is the view of Abu Haneefah and the literalists, and it is one of the two views of the madhhab of Ahmad.  

The same applies to all the other duties such as fasting the month of Ramadan, paying zakaah, and so on. 

If he did not know that alcohol is haraam and he drank it, then he is not to be subjected to the hadd punishment, according to Muslim consensus. They only differed with regard to whether he has to make up the prayers… 

The basic issue with regard to all of this is: are the laws obligatory for one who did not know them or is it the case that no one is under any obligation until after he comes to know? 

The correct view concerning this matter is that there is no obligation to adhere to a ruling unless there is the possibility of acquiring knowledge thereof, and nothing has to be made up if it was not known that it is obligatory. It is proven in al-Saheeh that some of the Sahaabah ate after dawn in Ramadan until they could tell the white thread apart from the black thread, but the Prophet (blessings and peace of Allah be upon him) did not instruct them to make up those fasts. Some of them used to remain in a state of janaabah (impurity following sexual activity or nocturnal emissions for which ghusl or full ablution is required) for a while and not pray; they did not know that it is permissible to pray with tayammum (dry ablution) – as happened to Abu Dharr, ‘Umar ibn al-Khattaab and ‘Ammaar. But the Prophet (blessings and peace of Allah be upon him) did not instruct any of them to make up the prayers. 

No doubt some Muslims in Makkah and in the wilderness continued to pray facing towards Jerusalem until news reached them that that had been abrogated (and the qiblah had been changed to the Ka‘bah), but they were not instructed to repeat those prayers. And there are many similar examples. This reflects the principle that the early generation and the majority of scholars followed, namely that Allah burdens not a person beyond his scope. Things are only obligatory when one is able to do them, and the punishment only applies when one fails to do something that is enjoined or does something that is forbidden, after proof has been established. End quote. 

Majmoo‘ al-Fataawa, 19/225 

Based on that, you do not have to make up any of the acts of worship that you did not know were obligatory. 

Our advice to you is to focus on learning the rulings of Islam and gaining understanding of the religion; try hard to learn Islam and follow it, and teach the next generation of Muslims, so that they will be able to face the challenges that face all Muslims, and especially in your country. 

We ask Allah to cause Islam and the Muslims to prevail. 

And Allah knows best.