I'm surprised that no one has thought of quoting the Qur'anic verses in context!
"Fight in the way of God against those who fight against you, but begin not hostilities. Lo! God loveth not aggressors.
And slay them wherever ye find them, and drive them out of the places whence they drove you out, for persecution is worse than slaughter. And fight not with them at the Inviolable Place of Worship until they first attack you there, but if they attack you there then slay them. Such is the reward of disbelievers.
But if they desist, then lo! God is Forgiving, Merciful.
And fight them until persecution is no more, and religion is for God. But if they desist, then let there be no hostility except against wrong-doers."
--Qur'an 2:190-193
This was written during a violent time for Muhammad, where He dealt with oath-breakers, and for the first seven years of his ministry, was completely pacifist. The result of this pacifism unfortunately led His followers to be harrassed, raped, tortured, killed, and discriminated against.
So if you read these Qur'anic verses, yes, God does allow a war, but ONLY if they are the aggressors and you are defending, since 'persecution is worse than slaughter.' And do not fight at the mosque, since, well, God doesn't like aggression. AND if they stop, then you must stop, and let them be.
This strongly contrasts to the Tanakh (Bible) and the commands of God to go outright into slaughter. In the Qur'an, there are rules and limitations.
But see the conclusions: God does not love aggressors. God is the Merciful, the Forgiving.