Is the AI to hostile?

Yeah all of the factions are apparently super warlike.  The only way they wont declare war is if you have a much larger army than they do.

Playing games on difficulty settings ranging from normal to challenging to hard, I have never had the AI declare war on me in something like 5 or 6 games (except, obviously when I walk into their cities with a cheesy rock giant). I play aggressively though.  Usually the AI are busy defending against me and my army of cheap, overpowered summons.

If you're not going to play militarily aggressively in games like this, then, as in real life,  you *must* have a well developed military deterrent, and you must aggressively pursue *diplomatic* avenues to stave off invasion. Develop treaties, trade routes, exchanges.  One way or another, even if you are not invading, you cannot ignore the AI, leave your military undeveloped, and hope to keep their greedy hands off your land. 

Click the diplomacy button, then the particular empire. The window on the right will list all modifiers to your diplomatic relations. If the negative ones outweight the positive ones, your relations will deteriorate over time.

The most significant negative modifier is "My army is stronger than yours". This gives a -2, -4 or -8 depending on how big the difference is. If you want a peaceful coexistence with your neighbors, make sure your armies at least match theirs

Yeah it is one of the things that bother me.  All of the nations are filled with evil bastards.  WTF!?  Why is every single person in elemental a warmongering psychopath?  The only way to keep the peace is by having  the largest army anyone has ever seen.  Since all the AI does is spam cities and armies, it means you have to no matter what victory condition you want to go for.  I could see some cultures being warlike... but all of them? Really? A world full of Spartans.

I Agree with Spyndel, I have never had a problem with the ai declaring war on me. They will declare war on the weaker nations and usually try to drag me into it. Look at the foreign relations screen and it will tell you clearly why the like, fear or don't like you.

Keeping up a solid military is a must, but you also get bonus points for diplomatic capital, You also get a bonus 1 for being of the same type (kingdom/empire)

I have had to be the one to declare war usually. Of course, this also depends on map size as closer proximity will probably elevate their fight/flight response.Playing 10 factions on a medium map will get you into wars very quickly. On a large map, not so much.

Maybe it's because I generally play on normal difficulty, but I do not find the AI to be too warlike.  If they sense weakness, then yes, they can attack.  But often there are warning signs (like demanding tribute).

We are not talking about the modern world, remember.  This is a fantasy world, and most (not all) fantasy worlds are loosely based on the middle ages, a dangerous time for more reasons than just disease and famine.  Hell, the pope would declare a crusade to send people off to kill each other in the holy land, just so they wouldn't spend so much time killing each other at home (and yes, I know this is a gross oversimplification, but it's still true).

PEACE through STRENGTH...  Ronnie Reagan  Them were some good years!  Ofc I was in College during the 87 recession but that was just a few years impact not like today's market...

Anyhow if the AI is giving you the beat down then change how you start so that you can have enough might to balance the AI's assessment of your strength and you'd find the AI to be as peaceful as ever.  The Game Start(first 10-20 turns) are critical though!

Good luck with it!

Amen to that.

Don't know how much 1.08 has improved AI yet, but in one of my 1.07 games, I had two AI opponents: Magnar and Capitar.  The Magnar completely dwarfed us both and the Capitar kept telling me, "The Magnar are really powerful, we have to stop them!".  However, the Capitar was at war with me and would never accept any kind of peace even though he was getting the crapped kicked out of him by the Magnar.

I was really hoping for some kind of Lord of the Rings alliance to go up against the might of Mordor, but alas the AI was too dumb to realize that.

I hope they have an aggression slider one day.  I would like to spend some more time exploring the game and the game world and not being forced into military escalation all the time.

Well, the price of freedom is eternal vigilance