"No compulsion in religion" is a popular canard among moderate Muslims.
There is no compulsion in religion. The right direction is henceforth distinct from error. And he who rejecteth false deities and believeth in Allah hath grasped a firm handhold which will never break. Allah is Hearer, Knower.
Except that renowned Islamic scholar Ibn Kathir said it's abrogated.
https://en.wikipedia.org/wiki/Ibn_Kathir
[Ibn Kathir] was a highly influential Arab historian, exegete and scholar during the Mamluk era in Syria. An expert on Tafsir (Quranic exegesis) and Fiqh (jurisprudence), he wrote several books, including a fourteen-volume universal history titled Al-Bidaya wa'l-Nihaya.
Tafsir of Ibn Kathir, Al-Firdous Ltd., London, 1999: First Edition, Part 3, pp. 37-38
1. Allah says: (meaning) do not force anyone to embrace Islam because it is clear, and its proofs and evidences are manifest. Whoever Allah guides and opens his heart to Islam has indeed embraced it with clear evidence. Whoever Allah misguides, blinds his heart and has set a seal on his hearing and a covering on his eyes cannot embrace Islam by force.
2. The reason for the revelation of this verse was that the women of Ansar used to make a vow to convert their sons to Judaism if the latter lived. And when the tribe of Bani an-Nadhir was expelled from Madinah, some children of Ansar were among them, so their parents could not abandon them; hence Allah revealed: , narrated by Ibn Jarir, on the authority of Ibn Abbas, Abu Dawud and an-Nasa’i, on the authority of Bandar, Abu Hatim, and Ibn Hiban from the Hadith of Shu’bah, Mujahid and others.
3. However Muhammad Ibn Ishaq narrated that Ibn Abbas said: it was revealed with regard to a man from the tribe of Bani Salim Ibn Awf called al-Husayni whose two sons converted to Christianity but he was himself a Muslim. He told the Prophet: "Shall I force them to embrace Islam, they insist on Christianity", hence Allah revealed this verse.
4. BUT, THIS VERSE IS ABROGATED BY THE VERSE OF "FIGHTING":
O Prophet, fight against the disbelievers and the hypocrites and be harsh upon them. And their refuge is Hell, and wretched is the destination. (At-Tauba 9:73), and He says: O you who have believed, fight those adjacent to you of the disbelievers and let them find in you harshness. And know that Allah is with the righteous. (9:123).
5.Therefore, all people of the world should be called to Islam. If anyone of them refuses to do so, or refuses to pay the Jizya they should be fought till they are killed. This is the meaning of compulsion. In the Sahih, the Prophet said: "Allah wonders at those people who will enter Paradise in chains", meaning prisoners brought in chains to the Islamic state, then they embrace Islam sincerely and become righteous, and are entered among the people of Paradise.
al-Wahidi is also certain the verse has been abrogated.
https://en.wikipedia.org/wiki/Asbab_al-Nuzul#History_of_Asbab_al-Nuzul_works
The earliest and the most important work in this genre is undoubtedly Kitab asbab al-Nuzul ("Book of occasions of revelation") of Ali ibn Ahmad al-Wahidi (d. 1075 CE). al-Wahidi mentions occasions of about 570 verses out of 6236 verses of the Quran. Wahidi's work is not only the first attempt to collect all the material regarding the occasions of revelation in one single volume, but it is also the standard upon which all subsequent works were based.
https://quranx.com/Tafsir/Wahidi/2.256
Al-Suddi said: “This verse was revealed about a man from the Helpers called Abu'l-Husayn. This man had two sons. It happened that some traders from Syria came to Medina to sell oil. When the traders were about to leave Medina, the two sons of Abu'l-Husayn called them to embrace Christianity. These traders converted to Christianity and then left Medina. Abu'l-Husayn informed the Messenger of Allah, Allah bless him and give him peace, of what had happened. He asked him to summon his two sons. But then Allah, exalted is He, revealed (There is no compulsion in religion…). The Messenger of Allah, Allah bless him and give him peace, said: 'May Allah banish both of them. They are the first to disbelieve'. This was before the Messenger of Allah, Allah bless him and give him peace, was commanded to fight the people of the Book. But then Allah's saying (There is no compulsion in religion…) was abrogated and the Prophet was commanded to fight the people of the Book in Surah Repentance”.
[ The "people of the Book" are the Jews and Xians, among some others. ]
But even if it's not abrogated...
https://quranx.com/Tafsir/Kathir/2.256
No Compulsion in Religion
(There is no compulsion in religion), meaning, "Do not force anyone to become Muslim, for Islam is plain and clear, and its proofs and evidence are plain and clear. Therefore, there is no need to force anyone to embrace Islam. Rather, whoever Allah directs to Islam, opens his heart for it and enlightens his mind, will embrace Islam with certainty. Whoever Allah blinds his heart and seals his hearing and sight, then he will not benefit from being forced to embrace Islam.''
It was reported that the Ansar were the reason behind revealing this Ayah, although its indication is general in meaning. Ibn Jarir recorded that Ibn `Abbas said that before Islam, "When (an Ansar) woman would not bear children who would live, she would vow that if she gives birth to a child who remains alive, she would raise him as a Jew. When Banu An-Nadir (the Jewish tribe) were evacuated from Al-Madinah, some of the children of the Ansar were being raised among them, and the Ansar said, `We will not abandon our children.' Allah revealed,
(There is no compulsion in religion. Verily, the right path has become distinct from the wrong path.)''
Let's be clear about what happened. Women vow that if their children survived, they would raise them Jewish.
So Allah (i.e. Muhammad) revealed the compulsion in religion verse.
https://quranx.com/Hadith/AbuDawud/Hasan/Hadith-2676
Narrated Abdullah ibn Abbas:
When the children of a woman (in pre-Islamic days) did not survive, she took a vow on herself that if her child survives, she would convert it a Jew. When Banu an-Nadir were expelled (from Arabia), there were some children of the Ansar (Helpers) among them. They said: We shall not leave our children. So Allah the Exalted revealed; "Let there be no compulsion in religion. Truth stands out clear from error." Abu Dawud said: Muqlat means a woman whose children do not survive.
The verse was about not compelling people to be Jewish. And that they were not compelled to stay Jewish, even if their mothers had made a vow. It was about justifying conversion from Judaism, and had literally nothing to do with converting from Islam.
Which makes sense that it was abrogated, since it was a temporary rule to justify a particular situation, until Muhammad could attain sufficient power.
The tafsir continues, and although it's not super-relevant, it's interesting and indicative.
Abu Dawud and An-Nasa'i also recorded this Hadith. As for the Hadith that Imam Ahmad recorded, in which Anas said that the Messenger of Allah said to a man,
("Embrace Islam.'' The man said, "I dislike it.'' The Prophet said, "Even if you dislike it.'')
First, this is an authentic Hadith, with only three narrators between Imam Ahmad and the Prophet. However, it is not relevant to the subject under discussion, for the Prophet did not force that man to become Muslim. The Prophet merely invited this man to become Muslim, and he replied that he does not find himself eager to become Muslim. The Prophet said to the man that even though he dislikes embracing Islam, he should still embrace it, `for Allah will grant you sincerity and true intent.'
"Embrace Islam.'' The man said, "I dislike it.'' The Prophet said, "Even if you dislike it.'' This is like saying "aren't you afraid of burning in hell?"
So, what are we left with?
https://quranx.com/5.33-34
The only reward of those who make war upon Allah and His messenger and strive after corruption in the land will be that they will be killed or crucified, or have their hands and feet on alternate sides cut off, or will be expelled out of the land. Such will be their degradation in the world, and in the Hereafter theirs will be an awful doom;
Save those who repent before ye overpower them. For know that Allah is Forgiving, Merciful.
When Islam has power, it's convert or be killed. This is Allah's word.
O Prophet! Strive against the disbelievers and the hypocrites! Be harsh with them. Their ultimate abode is hell, a hapless journey's end.
O ye who believe! Fight those of the disbelievers who are near to you, and let them find harshness in you, and know that Allah is with those who keep their duty (unto Him).
It is the duty of Muslims to fight the non-believers.
Warfare is ordained for you, though it is hateful unto you; but it may happen that ye hate a thing which is good for you, and it may happen that ye love a thing which is bad for you. Allah knoweth, ye know not.
Even if you don't like fighting, Allah knows best.
The "no compulsion in religion" thing is a lie told by the dishonest or parroted by the ignorant.