As a Buddhist how do I get over hatred towards my previous religion?

I am filled with genuine hatred towards my previous religion. My hatred is not directed towards other religions it's just towards my past. And this constantly bubbles up during meditation. I don't live in a majority Buddhist country and it was a long hard journey to arrive at the Dhamma. I don't have any problem with them following their respective paths but I am filled with rage for all the lies that were filled in my head for their own greed and ignorance. I get so enraged when I see people around me preaching non-sense theology to other people and to what effect, only to fulfil material desires. So, what is the strategy when you see the lies and ignorance around. Do you keep quiet as not to get into a debate to keep the 'Right Speech' or do you get into arguments? How do I get rid of hatred and tolerate other people spreading lies?