Is this "insistence by God to make war" in the Quran, or in the "hadith", or in later variant interpetations of the Quran?
Qur’an:9:5 “Fight and kill the disbelievers wherever you find them, take them captive, harass them, lie in wait and ambush them using every stratagem of war.”
That is like quoting a sentence from the bible and suggesting that the whole faith is based on that sentence.
The verse that you quoted is very often quoted by critics of Islam, to show that Islam promotes violence, bloodshed and brutality.
Critics of Islam actually quote this verse out of context. In order to understand the context, we need to read from verse 1 of this surah. It says that there was a peace treaty between the Muslims and the Mushriks (pagans) of Makkah. This treaty was violated by the Mushriks of Makkah. A period of four months was given to the Mushriks of Makkah to make amends.
Otherwise war would be declared against them. Verse 5 says: “But when the forbidden months are past, then fight and slay the Pagans wherever ye find them, and seize them, beleaguer them, and lie in wait for them in every stratagem (of war); but if they repent, and establish regular prayers and practise regular charity, then open the way for them: for Allah is oft-forgiving, Most merciful.” [Al-Quran 9:5]
Chapter 9 verse 6 gives the answer to the allegation that Islam promotes violence, brutality and bloodshed. It says: “If one amongst the pagans ask thee for asylum, grant it to him, so that he may hear the word of Allah; and then escort him to where he can be secure that is because they are men without knowledge.” [Al-Quran 9:6]
The Quran not only says that a Mushrik seeking asylum during the battle should be granted refuge, but also that he should be escorted to a secure place. In the present international scenario, even a kind, peace-loving army General, during a battle, may let the enemy soldiers go free, if they want peace. But which army General will ever tell his soldiers, that if the enemy soldiers want peace during a battle, don’t just let them go free, but also escort them to a place of security?
This is exactly what Allah says in the Quran to promote peace in the world.
http://theamericanmuslim.org/tam.php/features/articles/quran_95_commentary/