A famous bon mot asserts that opinions are like arse-holes, in that everyone has one. There is great wisdom in this… but I would add that opinions differ significantly from arse-holes, in that yours should be constantly and thoroughly examined.
We must think critically, and not just about the ideas of others. Be hard on your beliefs. Take them out onto the verandah and beat them with a cricket bat.... Be intellectually rigorous. Identify your biases, your prejudices, your privilege.