Without knowledge of islam dawah is useless and without patience, dawah is impossible. ALLAH swt has encouraged His true slaves to invite others to islam time and again in holy Quran.
Al-Quran 41:033
“Nobody’s assertions could be better (and more trustworthy) than the words of a person who invites others towards (the worship of) Allah, acts righteously and says, “Indeed, I am among those who surrender and submit (to Allah).””
In the verse above, ALLAH swt do not generalize the dawah for the high class clerics but it is for everyone because ALLAH swt describes dawah as an attribute of the believers, those who talk about ALLAH all the time and do not waste their times in lughw and false talks.
If we leave the work of dawah to those who we call scholars, then this will make islam look like other religions. For example, jews left the understanding of their religion to their clerics and priests, Christians did the same. Even today we see that very few people in both religions actually know their religious texts and others only do what they are told by those religious people to do. In fact the idea of knowing scriptures is not there in other religions as such.
It is islam that has made it must for its followers to not only understand it but also to spread its message till there is last muslim in this world. This is why Muhammad s.a.w.w said to spread and tells His message to those who were not present in the last sermon of His.
We should not left the dawah work on our scholars, they indeed are doing it, we should also learn Quran and hadith and spread its message and invite others to islam before we are asked on the day of judgment about this most important task. This is the real purpose of our living, now it depends on us as how we make others believe that their way of life is not true but they should be worshiping on God who is God of everyone.