Umar on Jahiliyyah: Islamic teachings will be abandoned if people do not know the time of ignorance

Ibn Taymiyyah reported: Umar ibn Al-Khattab, may Allah be pleased with him, said, “Verily, the foundations of Islam will undone one by one if there arises in Islam people who have never known ignorance.”

Source: Majmu’ Al-Fatawa

قال ابن تيمية قَالَ عُمَرُ بْنُ الْخَطَّابِ إنَّمَا تُنْقَضُ عُرَى الْإِسْلَامِ عُرْوَةً عُرْوَةً إذَا نَشَأَ فِي الْإِسْلَامِ مَنْ لَمْ يَعْرِفْ الْجَاهِلِيَّةَ

مجموع فتاوى ابن تيمية الآداب والتصوف تفسير سورة يونس

Hateful? Rude? Everyone Deserves Guidance

By Sheikh Salman al-Oadah at Islam Today

Someone who wishes to call other people to Islam has to be prepared to deal with those who are stubborn, rude, and downright insulting in their opposition to Islam and its message. This is one of the reasons why patience and tolerance are indispensable qualities for a Muslim preacher.
Persistence is another. No matter how much hostility and rudeness someone might exhibit when hearing about Islam, it is a mistake for a Muslim preacher to consider anyone a “lost cause.”