Praise be to Allah.
Words matter according to the great religion of Allah: by means of a word a person speaks, Allah may raise him in status, and by means of a word he speaks he may be doomed to Hell.
Allah says (interpretation of the meaning):
“Not a word does he (or she) utter but there is a watcher by him ready (to record it)” [50:18]
Al-Bukhaari and Muslim narrated from Abu Hurayrah that the Messenger of Allah (blessings and peace of Allah be upon him) said: “ A person may speak a word, not realizing what he is saying, and he will fall because of it into the Fire further than the distance between the East and West.”
Al-Tirmidhi narrated in a report which he classed as saheeh (authentic), that Bilaal ibn al-Haarith said: I heard the Messenger of Allah (blessings and peace of Allah be upon him) say: “One of you may speak a word that pleases Allah, and not know how far it reaches, but Allah will decree that He is pleased with him until the Day he meets Him. And one of you may speak a word that angers Allah, and not know how far it reaches, but Allah will decree that He is angry with him, until the Day he meets Him.”
Al-Nasaai narrated from ‘Abd-Allah ibn Buraydah that his father said: the Messenger of Allah (blessings and peace of Allah be upon him) said: “Whoever says ‘I have nothing to do with Islam’ and is lying, he is as he said, and if he is telling the truth, he will never come back to Islam soundly.”
Communism is a kind of atheism that is based on denial of the existence of God and veneration of the material, which it regards as the basis of all things. It does not value religion in general, any religion. Rather they regard religion as people's problems or as they say, the opium of the people, meaning that it distracts them from their material aims which form the basis of their ideology.
Undoubtedly this is one of the most dangerous kinds of kufr in the modern age, by which many people have been deceived and which has persecuted many people of religious commitment and faith.
Undoubtedly what is required of everyone who hears of this ideology and finds out about it is to reject it and to disavow himself of it and of its people before Allah. Veneration of this ideology, belief in it, promotion of it or love of it and its people cannot coexist with faith in the heart of anyone.
The one who joins them when he is aware of them and of the misguidance that they follow is a disbeliever in Allah the Almighty. If the one who says these words is ignorant of the basis of their ideology or has been deceived by their claims with regard to social and economic matters and their claims to care for the poor, to help them and to guarantee their rights, then he must be told of the real nature of this ideology and the danger it poses to religious commitment and faith, and that Allah has made His slaves independent, by means of the laws that He has revealed to them, of the need for any religion, sect or ideology other than that.
We suggest that any advice given to those who have been deceived by this ideology should be given in a kind and gentle manner, debating in a good way and explaining the evidence for that from sharee’ah (Islamic law). The one who engages in that should have sufficient understanding of this kafir un-Islamic) ideology and be skilled in debating and arguing, because most of those who are deceived by this ideology are very capable in argument and debate.
If he is indeed ignorant of this group and its origins, or he is ignorant of how it conflicts with the faith that is required of people, then he is excused for his ignorance. But if he persists, after things are explained to him, then he is a kafir (disbeliever) and an apostate.
We ask Allah to protect our faith and to help us avoid fitnah (trial and tribulation), both apparent and hidden.