Abaddon
Deity
Ok.. I have never even TRIED to win via a Diplomatic Victory... how do you go about doing it?
What level and map size are you attempting?
Basically dont destroy cities, trade with AI, and when you get to modern age build the UN, trade with and gift other civs, before UN vote sign ROP and even Mutual Protection Pacts with other civs and the vote should be yours
It is prefereable to choose a scientific tribe and choose scientific opponents, on low levels and standard and above map choose Russians and pop huts, gift you scientific freinds up at age changes and trade with them.
until the turn before he completed the UN, whereupon he made peace
I mean I thought that somebody you had ever been at war with at one time, even if you were at peace now, would not vote for you.