At the moment, if you are suffering, you cannot accept intrusive thoughts as ‘just a thought.’ You react to them as accurate or worried that you might act on the thoughts and cause some harm either to yourself or someone else. You have developed several ways to cope with your thoughts, including avoiding things or avoiding your thoughts.
Learning to accept your thoughts helps to stop the thought-action fusion. This is where you believe that thinking about something makes it more likely to happen.
Once you have been taught to accept them, the thoughts shall no longer mean anything to you with practice. They keep popping into your mind at the moment because you shine a spotlight on them, trying to figure out what they mean, trying to avoid them, and adopting various tactics to make sure you do not harm. Your brain has decided, ‘this is something we need to pay serious attention to.’ Learning to label them and move on helps to stop this.