(And had We willed, We would have raised a warner in every town.) `Calling them to Allah, but We have singled you out, O Muhammad, to be sent to all the people of earth, and We have commanded you to convey the Qur'an,'
لاٌّنذِرَكُمْ بِهِ وَمَن بَلَغَ
(that I may therewith warn you and whomsoever it may reach) (6:19).
Jihad with Qur'an (its propagation) is great Jihad
وَجَاهِدْهُم بِهِ جِهَادًا كَبِيرًا (And strive against them with it (the Qur'an) a great striving - 25:52). This is a Makkan verse when the injunction for Jihad, in the sense of fighting the infidels, had not been revealed. What is ordained in this verse is that you spread the message of Qur'an among the people at large. Propagation of Qur'anic message among people and to make them understand it is great Jihad whether it is by mouth, pen or any other means,
Tazkirul Quran
Maulana Wahiduddin Khan
In the Quran, the topics of the unity of God and the Hereafter have been described again and again in a number of different ways. If a man is serious, these discourses are enough to arouse his interest. But one who is unheeding is not influenced by any argument. Undertaking the great jihad by means of the Quran means a peaceful struggle to spread the word of God. That is to say, peaceful struggle is the real jihad—nay, the greatest jihad. Even if opponents try to divert the attention of the believers from the realm of peaceful efforts, it should then be the endeavour of the believers to concentrate upon the field of preaching based on the teachings of the Quran. However, if, due to the distraction caused by opponents, the field of action appears to be changing at any time, then all possible efforts should be made to bring it back to the field of peaceful activity aimed at conveying the message of the Quran.
Uthmani text of the Madinah mushaf (King Fahd Complex). Translation: Saheeh International. Tafsir via Quran.com.