I'm not a witness, but I'm 100% there's a Creator (God of the Bible). Why? He saved my life when I didn't believe in Him and finally decided to reach out for Him.
I used to have major problems like anger issues and other stuff. I never got counseling but He helped me to control it. When I would get angry, He'd tell me to calm down, take a walk, talk to Him and pour out my sorrows to Him. Usually I'd find myself in error and He would then push me (trust me, I never had any intention of forgiving anyone) to forgive.
I'll tell you now, I once was on the bus and I saw a lady with a pair of Beats headphones on and I thought "Look at that foolish woman, she paid 200$ for a set of headphones that costs 15$ dollars to make, she's a fool!" And He said to me the moment I finished the thought "Says the person wearing an 80$ pair of shoes that is made up of cheap rubber and fabric". All I could say was touche and never thought a word against her again. I never felt so put in my place in my life.
Now there's a lot of people out there saying "God doesn't exist" but that's not true. He does. I found Him because I was ready to be open to the idea that He did exist. Not only that, I reached my hand out to see if He was there, and He was. You best believe I was a bit surprised when I then saw He existed. I had lived my life doubting and denying His existence for so long it was pretty earth shattering.
Now if you're thinking about seeing whether God exists, you have to truly open up to the idea, and you have to reach for Him. When I reached for Him, I wasn't holding onto doubt, but I wasn't in belief either. I was throwing it all up, not knowing if I was to be caught or to fall.
Does God exist? Absolutely 100% Is His name Jehovah? No. Is He with the organization? No. Does He have a specific organization? No. His name is YHWH and He has a Son. There are many believers out there that belong to Him.