I would love to be someone who could state that nothing in the paranormal world can harm your spirit. But by my own personal experience I cannot say that. I know evil exists. I don't know why it's here, I don't know where it came from, I don't know if it can truly harm my soul, but I know it when I run across it and I try to stay far far away. I've just had too many dealings to pretend it doesn't exist.
So yeah, when you open the door to the paranormal you might attract entities with negative intent. But there are many many positive benefits as well that I think if you can learn to protect yourself and vibrate at a high frequency then you're a-okay. It's a choice.
One thing my guides told me recently when I was really reticent to open myself back up was that there would indeed be times when I got scared, when I saw something scary or something scary came up to me, but by blocking those experiences I was also blocking the good experiences too. They told me, "If something scares you, be scared. Then get over it and get back to the good stuff." (I'm paraphrasing, they don't say "stuff"

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Because I opened myself back up (but in a healthy and positive, high vibrational way) I was able to tap into my abilities as a clairvoyant, clairaudient, and medium. Now I'm using those abilities to help other people, especially other lightworkers, wake up and get moving in the direction they intended. I am so fulfilled by this work I can't even describe my joy.
And that journey has made me wonder how many other lightworkers have turned off their abilities because of the fear of the negative. I certainly don't blame them. I've seen things that have turned my soul inside out with fear. But I wouldn't trade my journey for anything.