Which of the two noble verses was revealed first: "And whoever does not judge by what Allah has revealed – then it is those who are the defiantly disobedient [Al-Fasiqun]" or "And whoever does not judge by what Allah has revealed – then it is those who are the disbelievers [Al-Kafirun]," and does one abrogate the other?

Knowing the reason for the revelation of verses and the context in which they were revealed helps in understanding them. These verses came in the context of discussing the People of the Book and were revealed regarding the case of the adulterous Jew for whom they changed the ruling of stoning in the Torah. The Jews concealed legal rulings such as stoning, and whoever did not rule by what Allah revealed was considered impious (fasiq), an unbeliever (kafir), or an oppressor (zalim). The Jews were described as unbelievers for concealing the rulings of the Torah, and as oppressors for not being just towards the wronged. The lesson is in the generality of the wording, not the specificity of the reason; thus, anyone who does not rule by what Allah has revealed is subject to these descriptions. These verses were revealed concerning rulers, while other verses speak about those who seek judgment, such as His saying, the Almighty: (But no, by your Lord, they will not believe until they make you judge concerning that over which they dispute among themselves). The order of the verses in the Quran is: (And whoever does not judge by what Allah has revealed - then it is those who are the disbelievers), then (And whoever does not judge by what Allah has revealed - then it is those who are the wrongdoers), then (And whoever does not judge by what Allah has revealed - then it is those who are the defiantly disobedient). There is no abrogation among these verses, and Surat Al-Ma'idah is among the last chapters of the Quran to be revealed.