I've changed the way I preach. I often qualify what I speak by saying something like, "That's what I believe, now you have to ask God if it's true" or "You can believe what you want. Aren't you glad you don't have to answer to me?" Some people may think that that takes away from the power of preaching but I think it's a much more honest approach.
I grew up as a Christian listening to preachers that were convinced that every word they spoke was sent from heaven. Their passion and strong conviction impressed me. I believed everything they said and wanted to be just like them. But as years went by and I grew in my relationship to God I started to question my mentors. Some of the things they said were just plain wrong. I'm sure they thought they were right at the time but now with new information and new experiences under my belt, I could see that they were misguided.
Those experiences have made me cautious in both how I listen and how I speak. It's made me slow to buy everything I hear and temper my desire to proclaim "the truth". Not that I don't believe what I say is true, but I have to understand that I'm fallible. I hear things through my own filters and dysfunction. I do my best to check my thoughts against what other people have said but when it comes right down to it, only God knows the truth.
Now, there are some things that I'm rock solid about - the basics of the faith - Jesus coming and dying for our sins, etc. I'm talking more about how we apply our beliefs to daily life or maybe those debatable passages in scripture or doctrines of the church.
Occassionally someone will come up to me after I speak and say, "You really nailed that!" "That was exactly right!" I don't know how to respond because they may only be saying that they see life through the same filters that I do. Or then again, maybe I did get it exactly right!
My point in all of this is that in both speaking and listening we have to be humble. As much as it feeds our ego, we can't always be confident that we are proclaiming or hearing truth. We need to welcome the Spirit of God into our lives to show us what is true... it may take years for some things to click. Only then will we know if what was proclaimed was true or false.