Make sure you have 20-25 worshippers at your alter(or more if you constantly use miracles). When he sends all the armies in the old greek town towards you, use rocks around your town to fend them off as they come up the hill to your town.
Also, make sure you rescued your men. They are VERY important and hold many men. Have your creature know heal and fire miracles, and make sure you have the Death, Life and Shield miracles(Shield and Life, more importantly). Also also make sure you have walls all around your town, no gaps, no open spots, no open gates. Make some archers to be on your walls if your a weak noob. Be prepared once you have impressed/taken 2 towns(I think 2), the Undead creature is found, and starts running around smacking your walls.