At-Tawbah (Arabic: التوبة, "The Repentance"), also known as Barā’ah (Arabic: بَرَاءَة, - "act of setting free or getting red of obstructions by customs"), is the ninth chapter (sūrah) of the Quran. It contains 129 verses (āyāt) and is one of the last Medinan surah.
This particular verse and other verses have always been targeted for the purpose of accusing Islam as being violent and ordering Muslims to kill disbelievers.
I have an online lecture I delivered a few years ago, addressing this verse, and in shaa Allah it will benefit you in giving a comprehensive answer to this question:
It is permissible and recommended to say Bismillah on starting any important act including Quran recitation, but you should not say it as a verse when you recite Sura Tawbah because it has no Bismillah Arrahman Arraheem.
It was to counter the attack and plans of the enemies of Islam and Muslims. Islam orders Muslims to fight against the enemies who plan and try to attack Muslims, but to be peaceful with those who do not attack Muslims (Allah does not forbid you to deal nicely and kindly with those (Non Muslims) who fought not against you on account of religion nor drove you out of your homes (Sura 60, Verse 8).