If Allah wanted to create a world without war, He would grab every war-maker the second they make an intention. (Qur’an 2:253). Every man would walk on this earth with chains on him and angels monitoring every one on His command and no one will allowed to do anything except what is right.
But Allah did not want to create such a world.
Allah has a plan to create a perfect world known as Paradise. But only those who are obedient to Him will enter it.
So He created different creations and offered them a choice. Take a small test of His of some decades and then He will grant them eternal life in Paradise. Some creations agreed, other did not (Qur’an 33:72).
In this world, every good person will express how they good they are and every evil person will express how evil they are (Qur’an 20:15). So when they are called to account, their own actions will serve as evidence and the matter of Paradise and Hell will be done in justice (Qur’an 35:37).
For this test to function, Allah will not seize every evil-doer on the spot. So He delays judgment to the Last Day. (Qur’an 16:61)
If Allah does intervene in this world, it is either to ensure the world continues to function (Qur’an 22:40), sometime it is to test, sometime it is to shed sins off people and let them earn their good deeds for Paradise, sometime it is cause death for those whose time is up in whatever manner He chooses, sometime it is to reward in this life out of His grace, sometime it is to punish in this world and make an example regardless if people will refuse to take heed from example. It’s not guaranteed He will intervene but He does so according to His wisdom while ensuring the test remains in tact.
In Jihad case, Allah has made it clear when He will help someone. That they need to be evidence that some oppression has occurred, the war will be started by a government that is both morally upright and in power, and in case of Muslims, ratio must be at least 1:2 (current situation, Muslim countries aren’t even 1:10). If these conditions aren’t met, then the oppressed should stay put and try not to start war. Violating this law of His and choosing to cause chaos will result in Him making you taste the consequences of the violation. (Qur’an 6:65)