That can be rather frustrating.
Fortunately, thinking is a skill. And, like any skill, you can improve thinking through instruction and practice.
Here are some excellent, short videos introducing different aspects of critical thinking. Since they’re introductory, don’t expect a lot of detailed information. But I could see using these to start discussions on what it means to think well and how each of these relates to studying the Bible and theology.
I found the fourth video on “getting personal” particularly helpful. Although I think most people intuitively know that you shouldn’t disagree with someone just because you don’t like them (and, conversely, you shouldn’t agree with someone just because you do like them), this is still such an easy mistake to make that we all need to be reminded of it.