Well, let's look at the historical facts as viewed from an Islamic point of view.
Quran 9:29 interpretation
Verse 9:29 is a command to fight the Byzantine Romans and other hostile powers who were planning an invasion against the Muslims in Arabia. In context, it is a distinct response to aggression, in particular the assassination of one of the Prophet’s ambassadors.
Allah said:
قَاتِلُوا الَّذِينَ لَا يُؤْمِنُونَ بِاللَّهِ وَلَا بِالْيَوْمِ الْآخِرِ وَلَا يُحَرِّمُونَ مَا حَرَّمَ اللَّهُ وَرَسُولُهُ وَلَا يَدِينُونَ دِينَ الْحَقِّ مِنَ الَّذِينَ أُوتُوا الْكِتَابَ حَتَّىٰ يُعْطُوا الْجِزْيَةَ عَن يَدٍ وَهُمْ صَاغِرُونَ
Fight those who do not believe in Allah or in the Last Day and who do not consider unlawful what Allah and His Messenger have made unlawful and who do not acknowledge the religion of truth from those who were given the Scripture, until they give the tribute willingly while they are humbled.
Surah At-Tawba 9:29
On the surface, this appears to be an open-ended command to fight non-Muslims until they are conquered. However, a fundamental principle of Quranic exegesis (tafseer) is that the verses must be understood in the context in which they were revealed (asbab an-nuzul) and in conjunction with other verses delineating the rules of warfare.
The problems:
It all started when the messenger of Muhammad was killed.
Why was he killed?
Because he committed "Blasphemy".
The messenger of Muhammad carried a letter in which stated that the Byzantines were believing in a false God (Jesus Christ) and that they should immediately surrender to Allah (the only real God).
In those times "Blasphemy" was strictly penalized by death.
Without asking any explanation the Muslims attacked the Byzantines in what was called the battle of Mu’tah.
The Muslims attacked when in reality they were never attacked and the messenger was killed because he committed a crime inside Byzantine's territory.
Quran 9:29 was actually revealed after the battle of Mu'tah during the expedition of Tabuk.
Muhammad heard the Byzantines were planning on attacking the Muslims.
He and his army soon realized the rumors were incorrect and there was no attack planned.
He and his army were returning and that's when the verse was revealed.
The verse is meant to justify the attacks on Christians and Jews towns on their way back and collect Jizyah from them.
The interpretations of the Tafseer are not Quranic, they are human manipulations of the real scriptures.
Why should we believe what the so-called Scholars believe Allah's intentions were?
