Why does god use squabbling, bickering humans to spread his word when he could just write it in the stars?

He does! but humans are so blind and so wrapped up in ourselves that we do not see his signs! God spreads his word to me every day when I'm out walking in our woods out back - he's all around me. Birds do sing god's word, spiders weave it in their webs, trees grow it in their tree leaves, and people who are looking for it notice. everyone else is too wrapped up in their daily business to listen.