There is a difference between believing in the doctrine of divine healing and exercising personal faith to receive your healing. Many would tell you that they believe that Jesus took their sicknesses and that by His stripes they are healed, yet they stay sick. Why? They make the mistake of thinking that faith in the doctrine of divine healing is the same as faith that actually TAKES that healing and makes it theirs.
You can believe that Jesus paid for your healing and still not be healed! Healing only comes when you “believe you receive it when you pray”. It’s not enough to “believe” it; you also have to “receive” it!
I knew how to be saved before the day that I got saved. Someone had already told me how to do it. I mentally assented to the concept that Jesus paid for my sins and I could be born again by receiving Him. But that level of “faith” did not save me. The devil and his demons know that it’s true, too, but it’s not benefiting them. My life only changed when I actually received Jesus.
Your healing will not start to manifest itself in your body until the point that you receive your healing. It’s not enough to mentally assent to the fact that Jesus paid for it 2000 years ago by taking your diseases Himself. It’s not enough to know that it’s available to you. That’s a good start, but you need to make it personal and receive your healing.