So, i have never been hit by a god yet, but we have sent 4 gods on official server onto other clans as to secure our position. I can tell you they feel very OP and while you get 60 seconds of gratification there is no real PVP element to it. Summon from a well planned position and almost no amount of counter attack could ever stop you.
The real problem is that avatars simply walk over everything and destroy it. Tier 1, Tier 2, Tier 3. Vaults all they have to do is move. To fix this make the walk only destroy tier 1 structures. Make them have to attack tier 2 one time and tier 3 two times. Perhaps change some of the attack times of the avatars to adjust for this type of scenario.
2nd problem -> No counter-play. you can't really shoot arrows at the guy or run up and melee him as the god is standing on his head wrecking everything just by existing. Unless the person is really careless and you catch him in the 10-15 seconds of the start of the summon your pretty much screwed. To fix this make the summon time 60 seconds to 5 minutes. This means you need to find a good spot, you need to protect the person during the summon (lots of clever ways to do this). They might have to walk the summon a bit further as the added protection is needed. The "defenders" have some little chance at an outplay or some counter-play. Perhaps Make the person who is doing the summon gain 50% dmg reduction as summons will take much longer and your devotion to your god is showing.
TLDR: Avatars a bit to much but maybe not. If you have used them or have had them used on you post here what you think.