All human beings have intrusive thoughts, images and urges that the do not want, (e.g. having the urge to push someone onto a rail way track, or worrying that the gas tap on the cooker might still be on).
Suffering from Intrusive Thoughts doesn’t not mean you are dangerous if you have thought about pushing someone onto a railway track for e.g.,) you have done nothing wrong it’s just the meaning you are attaching to your thoughts and then in turn they become more frequent and distressing, and over time the affect all areas of your life.
Those who suffer with OCD have intrusive thoughts more frequent and complex than people who don’t suffer from OCD, because they become more distressed by them, and by the meaning they attach to the thoughts and the way they have responded to them.