The uneasiness of the three kingdoms to attack made them delay the actual start of war. They delayed it for two weeks in hopes that they could actually avoid it but the pressure that the Church of Light is weighing down on them. The kings of each kingdom are also said to be guarded by angels but in truth they are threatened with actual angels beside them.
It is also not helping them that some of the nobles in their kingdoms are greedy. They were much easily coerced by the angels when they said that they need to attack Avalon because the demons are planning on raining chaos. The nobles that are in the side of reason wanted to argue but the presence of the angels is dangerous even to them as they have been made aware.