(… فَإِنْ حَاجُّوكَ ) (So if they argue with you …): This is a proof that Islam is a religion of argument, proof, evidence and convincing. Prophet Muhammad (saws) used to argue with the Jews, who used to be the most insisting and arguing people and provide proofs to them at that time. Abduallah Bin Salam, who was a Jew cleric and converted to Islam, told Prophet Muhammad (saws) that:

‘The Jews are liars[1].’

(… فَقُلْ أَسْلَمْتُ وَجْهِيَ لِلَّهِ …) (…say, “I have submitted myself to Allah [in Islam],…): So, after the proof and evidence are submitted, yet, they (the Jews) denied them out of jealous animosity between them and altered the knowledge they had, you say: ‘I have submitted myself to Allah in Islam” in a good manner.

(… وَمَنِ اتَّبَعَنِ …) (…and [so have] those who follow me.”…): It’s not only me but also those who follow me. We’ve all submitted ourselves to Allah in Islam. They obeyed Allah (swt) and followed His orders.

(… وَقُل لِّلَّذِينَ أُوتُوا الْكِتَابَ وَالْأُمِّيِّينَ أَأَسْلَمْتُمْ …) (…And say to those who were given the Scripture and [to] the unlearned, “Have you submitted yourselves?”…): The unlearned are the Arabs of the Arabian Peninsula, and those who were given the Scripture are the Jews and Christians. The Jews, however, were more than the Christians in the Arabian Peninsula.

(… فَإِنْ أَسْلَمُوا فَقَدِ اهْتَدَوا ۖ وَّإِن تَوَلَّوْا فَإِنَّمَا عَلَيْكَ الْبَلَاغُ …) (…And if they submit [in Islam], they are rightly guided; but if they turn away – then upon you is only the [duty of] notification …): This is what our religion is about. They are rightly guided when they convert to Islam. Yet, if they don’t, you only have the duty of notification:

 {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)

This verse is indicative of the freedom of belief as stated by the Almighty:

{ وَقُلِ الْحَقُّ مِن رَّبِّكُمْ ۖ فَمَن شَاءَ فَلْيُؤْمِن وَمَن شَاءَ فَلْيَكْفُرْ}

(And say, “The truth is from your Lord, so whoever wills – let him believe; and whoever wills – let him disbelieve.”) (Al-Kahf: 29)

( وَاللَّهُ بَصِيرٌ بِالْعِبَادِ … ) (…And Allah is Seeing of [His] servants): Allah (swt) is Seeing, All-Knowing and All-Aware of what they say or do.

[1] Hadith no. 4210, Chapter: Surat Al-Baqara, Prophetic Commentary on the Qur’an (Tafseer of the Prophet (pbuh)), Sahih Al-Bukhari