Islam Q&A say that:
"Ahl as-Sunnah wa’l-Jamaa‘ah are unanimously agreed that the Arabs are superior to others in terms of descent and lineage, and that regarding the Arabs as superior is in general terms, and does not apply at the individual level."
Well nationalism or love for the nation doesn't mean love for individuals, it mean love and pride for whole nation and its particular culture, language, descent and lineage.
Today Arab nationalists use such scholarly opinions to prove their superiority as a nation over non-Arab muslims such Persians and Turks.
On the other hand anti Islam groups use such scholarly opinions to create doubts in the minds of non-Arab muslims.
From the fragmentation of Abbasid Caliphate till WWI it were mainly non-Arab nations who carried the flag of Islam and today Arabs don't even make 1/4 of total global muslim population.
So why should non-Arab muslims consider their nation, their descent and their lineage lesser than Arabs? Why shouldn't they feel pride over their nation?
To sum all this in one question,
Why non-Arabs are considered lesser than Arabs as a nation and how can we justify this to non-Arab muslims?