With regards to the virtue of having both knowledge of the Religion as well as eemaan, Imam al Qurtubee (rahimahullah) mentions about the aayah:
<<Allah raises in rank those from you who have eemaan (true faith) and those who have been given knowledge.>>
Soorah Mujaadilah (58) aayah 11
Meaning (He raises) in reward in the Hereafter, and in nobility in this worldly life. So He raises the believer over the one who is not a believer and (He raises) the scholar over the one who is not a scholar.
And ibn Mas’ood said: Allah praised the scholars in this aayah. And the meaning is that Allah raises those who have been given knowledge over those who have eemaan but have not been given knowledge. In rank – meaning ranks in their religion when they act upon that which they have been commanded to do.
(Tafseer al Qurtubee)
With regards to the excellence of the people of knowledge, the Shaykh Abdur-Rahmaan as Sa’dee rahimahullah mentions about the aayah:
<<Allah bears witness that none has the right to be worshipped except Him; and the angels and the people of knowledge (also bear witness to this). He maintains His creation with Justice. None has the right to be worshipped except Him, al Azeez, al Hakeem.>>
(Soorah aale ‘Imraan (3) aayah 18)
And in this aayah is (mentioning of) the virtue of knowledge and the people of knowledge – because Allah singled them out with making mention (of them) to the exclusion of other people; and linked their shahaadah (bearing witness) with His shahaadah and His angels’ shahaadah.
And He made their shahaadah to be from the greatest evidences and proofs for His Tawheed and His Religion and His Recompense.
And that it is obligatory for the mukallafeen (those who are Islamically accountable for their actions) to accept this just and truthful shahaadah.
(Tayseer ul Kareem ir Rahmaan of as Sa’dee)