Someone may wonder why such repetition is there. The answer is that no repletion is there, and we have to consider the Quranic context of the verse.

(… مِن قَبْلُ هُدًى لِّلنَّاسِ ) (Before, as guidance for the people.…): The Torah and the Gospel had been revealed, before the Quran was sent down, for the guidance of people. What’s guidance? It’s to show the straight path. That’s why the verse reads:

(… وَأَنزَلَ الْفُرْقَانَ …) (…And He revealed the Qur’an …): After it’s mentioned that the Torah and Gospel had been revealed before the Quran with the goal of showing that the Quran is also a guidance to people so that no one would think that the past Books are the only guidance to people. Thus, repetition is made to highlight the sending down of the Holy Quran.

The Holy Quran is named as ‘Al-Furqan’ in Arabic in this verse, and this word means that it separates the right from the wrong when there is a conflict between them as between the good and the evil.

(… إِنَّ الَّذِينَ كَفَرُوا بِآيَاتِ اللَّهِ لَهُمْ عَذَابٌ شَدِيدٌ …) (…Indeed, those who disbelieve in the verses of Allah will have a severe punishment ): So, the disbelievers, after all the rhetoric and persuasion by proof and evidence, will have a severe punishment by Allah (swt). Anyhow, we never force anyone to convert to Islam as the Almighty tells His Prophet, Muhammad (saws):

 {فَذَكِّرْ إِنَّمَا أَنتَ مُذَكِّرٌ* لَّسْتَ عَلَيْهِم بِمُصَيْطِرٍ}

(So remind, [O Muhammad]; you are only a reminder. %  You are not over them a controller.) (Al-Ghaashiya : 21-22)

( وَاللَّهُ عَزِيزٌ … … ) (…and Allah is exalted in Might,): The Exalted in Might is the one who’s never defeated. Besides, it can also mean the one who can do without the worshipping of all people as stated in the Qudsi Hadith:

“O My servants, were the first of you and the last of you, the human of you and the jinn of you to be as pious as the most pious heart of any one man of you, that would not increase My kingdom in anything. O My servants, were the first of you and the last of you, the human of you and the jinn of you to be as wicked as the most wicked heart of any one man of you, that would not decrease My kingdom in anything.[1]”

Hence, Allah (swt) is needless of our worship.

( ذُو انتِقَامٍ … ) (…the Owner of Retribution): This is due to rejecting the belief in Allah (swt) and denying His blessings.

[1] Hadith no. 2577, Sahih Muslim