Qur’anic verses in favor of violence
Quran in chapter 9 says,
"Freedom from (all) obligations (is declared) from Allah and His Messenger to those of the Mushrikun (polytheists, pagans, idolaters, disbelievers in the Oneness of Allah), with whom you made a treaty.
So travel freely (O Mushrikun) for four months (as you will) throughout the land, but know that you cannot escape (from the Punishment of) Allah, and Allah will disgrace the disbelievers.
And a declaration from Allah and His Messenger to mankind on the greatest day (the 10th of Dhul-Hijjah — the 12th month of Islamic calendar) that Allah is free from (all) obligations to the Mushrikun and so is His Messenger. So if you (Mushrikun) repent, it is better for you, but if you turn away, then know that you cannot escape (from the Punishment of) Allah. And give tidings (to Muhammad) of a painful torment to those who disbelieve.
Except those of the Mushrikun with whom you have a treaty, and who have not subsequently failed you in aught, nor have supported anyone against you. So fulfill their treaty to them to the end of their term. Surely Allah loves Al- Mattaqun (the pious — see V.2:2).
Then when the Sacred Months (the Ist, 7th, 11th, and 12th months of the Islamic calendar) have passed, then kill the Mushrikun wherever you find them, and capture them and besiege them, and prepare for them each and every ambush. But if they repent and perform As-Salat (Iqamat-as-Salat), and give Zakat(charity), then leave their way free. Verily, Allah is Oft-Forgiving, Most Merciful.
And if anyone of the Mushrikun (polytheists, idolaters, pagans, disbelievers in the Oneness of Allah) seeks your protection then grant him protection, so that he may hear the Word of Allah (the Quran), and then escort him to where he can be secure, that is because they are men who know not."
—Muhsin khan translated Quran, verse 9:1-6
"O you who believe (in Allah’s Oneness and in His Messenger (Muhammad)! Verily, the Mushrikun (polytheists, pagans, idolaters, disbelievers in the Oneness of Allah, and in the Message of Muhammad) are Najasun (impure). So let them not come near Al-Masjid-al-Haram (at Makkah) after this year, and if you fear poverty, Allah will enrich you if He will, out of His Bounty. Surely, Allah is All-Knowing, All-Wise. 
Fight against those who
(1) believe not in Allah,
(2) nor in the Last Day,
(3) nor forbid that which has been forbidden by Allah and His Messenger
(4) and those who acknowledge not the religion of truth (i.e. Islam) among the people of the Scripture (Jews and Christians), until they pay the Jizyah with willing submission, and feel themselves subdued. 
And the Jews say: 'Uzair (Ezra) is the son of Allah, and the Christians say: Messiah is the son of Allah. That is a saying from their mouths. They imitate the saying of the disbelievers of old. Allah’s Curse be on them, how they are deluded away from the truth! "
—Muhsin khan translated Quran, verse 9:28-30
Quran chapter 8 says,
“(Remember) when your Lord inspired the angels, “Verily, I am with you, so keep firm those who have believed. I will cast terror into the hearts of those who have disbelieved, so strike them over the necks, and smite over all their fingers and toes.”
This is because they defied and disobeyed Allah and His Messenger. And whoever defies and disobeys Allah and His Messenger, then verily, Allah is Severe in punishment.”
—Muhsin khan translated Quran, verse 8:12-13
“Say to those who have disbelieved, if they cease (from disbelief) their past will be forgiven. But if they return (thereto), then the examples of those (punished) before them have already preceded (as a warning).
And fight them until there is no more Fitnah (disbelief and polytheism: i.e. worshipping others besides Allah) and the religion (worship) will all be for Allah Alone [in the whole of the world]. But if they cease (worshipping others besides Allah), then certainly, Allah is All-Seer of what they do.”
—Muhsin khan translated Quran, verse 8:38-39