Is a religious experience evidence for God?

So many of my friends and relatives who are believers tell me that they "know" god exist because he has spoken to them or they have been touched by the holy spirit  but I am not convinced. I think I understand that they are speaking of a feeling. A feeling of euphoria or peace or just incredible happiness. I have had it too. I have it when I hear a certain song or hear my grandchild cry for the first time. I have that feeling when my children tell me they love me  and when my dogs cuddle with me. Sometimes it is stronger than others but it is, nevertheless, a wonderful feeling. When I was a believer it happened in church and I called it a religious experience, but does it prove that god exist? I think not.

As I have grown in age and knowledge, I have come to understand that whatever the feelings we have in our bodies begin in our brain. Good or bad, pain or pleasure it is all in our heads, literally. I have a great deal of pain at times and though it is real pain, I can take a pill that blocks that pain by affecting my brain. I'm not a doctor but my understanding is that certain chemicals can interrupt the messages received by the brain. Pain medication does not cure the problem but interrupts the signal and therefore makes me feel that the pain is gone. I think religious experience is similar in that the brain is affected by some stimuli and reacts by flooding the body with happy chemicals.

I recently read an article by Dan Barker of FFRF fame and he has some interesting things to say:

God is imaginary.

But imagination is real.

So . . . the religious experience is a real experience. It happens to many believers in all religions. It happened to me.

It can STILL happen to me. Even as an atheist, I can make my mind go back into the “religious experience” mode and relive all those very real feelings. (What a weird sensation for a nonbeliever! I don't do it very often, but every couple of years, when I am all by myself, I will try it out, just to see if my brain has changed.) They are powerful and motivating feelings. When I was a believer, those experiences, though not necessary for my faith, were very confirming of my faith.

I particularly like his analogy to the monster at the window:

For example, you wake up one night screaming from a nightmare, sitting up straight in bed. You wake up the whole house. Your palms are sweating. Your heart is racing. Your breathing is quickened. No one can deny that you have had a very real and powerful experience. But there is no monster crawling through the window.
It is all in your mind.

So now what can I say to my friends when they say they "know" god is real because they have had a religious experience? Nothing, because they would only be angry because I am trying to spoil their fantasy, and they wouldn't believe me anyway.