You can cling tightly to your beliefs, or you can have an open mind. Decide which you want.
Clinging tightly to a belief is not a profitable strategy for learning new things. If you must cling to a belief, cling with a child's grip.
People who cling tightly to beliefs seal off their minds to input from others. That's basically what it comes down to.
The more firm beliefs you have, the more closed-off your mind is.
Clinging tightly to a belief makes the belief religious in nature, regardless of whether it involves God or not.
What are you religious about? Perhaps it's gun control, abortion, the death penalty, patriotism ("America is the greatest country on earth"), deficit spending, taxation, evolution, global warming.
If you have religious beliefs about non-religion topics, it means you have a closed mind. Never a good idea.
Why are you defending your own religiosity? Do you not see how that makes you look? How it makes you sound?
Having religious beliefs about non-religious things is absurd.
Having religious beliefs about religious things might also be absurd. Are you even open to that possibility?
"I don't have an open mind about certain things" is the hallmark of a stunted mind.
Everything you know is wrong until proven otherwise. Proven, as with facts. Not with beliefs.
Don't be so defensive.
Take your mind out of the root cellar and let it breathe.
If you're confident in your beliefs, you can allow fresh ideas in without being defensive.
If you feel strong emotions (like anger) when debating a given topic, you're not being rational. Just admit it. Out loud. To yourself. To others.
Get off your high horse. You don't know half as much as you think you do.
"Doctrinaire" is a variant of "jerk."
Don't be a jerk.