In ancient Makkah the Quraysh had placed the idols of all the tribes in the Kaabah. Arab tribes from far off places came to visit the Kabah in order to venerate the idols. The Prophet of Islam used to go to the camps of these idolatrous tribes and call them to the one God. The details of his efforts are recorded in his biography.
Once he visited the camp of the tribe of Banu Shayban ibn Thaalaba. He said to them: “I call you to bear witness to the one God. For there is no god but the one God.” The chiefs of the tribe rejected his call and said, “We live on the border of Persia and the Emperor of Persia has taken an oath of allegiance from us that we will not indulge in anything new (i.e. abide by the status quo) and that we will not welcome anyone who does so.” (Hayat as Sahaaba 1/101-102)
The Prophet of Islam had called upon the tribe to engage in a purely non-political action, so why did they answer in this manner? The reason was that in ancient times religion was regarded as a matter for the state to decide.
To believe in a religion or invite people to accept a new religion required the permission of the state. Propagating a new religion without such permission was equivalent to treason and as such could incur the harshest punishment.
This is why we find cases of religious persecution in every country in ancient times. The Jews in their heyday persecuted the Christians. When the Christians acquired political power, they in turn subjected the Jews to persecution. In India the Hindu kings persecuted the followers of Buddhism. None of them wanted to launch a political movement. They functioned in a non-political field, yet they were subjected to persecution.
Religious persecution was resorted to in every part of the world. Religious matters depended wholly on the will of the king and no king was willing to give religious freedom to his people. That was why the propagation of religion was the most difficult of tasks.
After a long historical process, the age of religious persecution has been replaced with total religious freedom all over the world. One article of the declaration issued by the leaders of the French revolution on August 26, 1789 was:
“Everyone has the right to freedom of thought, conscience and religion; this right includes freedom to change his religion or belief, and freedom either alone or in community with others and in public or private, to manifest his religion or belief in teaching, practice, worship and observance (EB X-1050).
Then after World War II, when all the nations of the world came together to form the United Nations, their organization issued a Declaration, subscribed to by all in June 1948 known as the Universal Declaration of Human Rights. This charter accepted with greater force that “every man or woman enjoys the right to opt for any religion according to his or her will, and may propagate it peacefully.” This declaration was signed by all the nations of the world. (X/1050)
This Declaration of the United Nations was accepted by all the nations and was made part of the constitutions of all the Signatories. For instance, the Indian constitution, written after 1947, included article No. 18 in which every Indian citizen has been granted the freedom to practice and propagate his religion.
This religious freedom is a very great blessing of God which has come to the world after a thousand years. This freedom has increased dawah opportunities exponentially.