By that criterion anyone who has a revelation has a right to believe in God, and anyone who doesn't has a right to remain an Atheist. I think most Christians would be perfectly happy with that. But I wouldn't consider such an experience to be a counterexample of anything. Lots of people have experiences like that. I had experiences myself rather like that when I was a Christian, and so have a lot of other people who have since left the church.

However, if we start with your criterion, Why shouldn't the Atheists be willing to accept the existence of God on the basis of other people's experiences of him/her/it? I've never seen India, but I'm certainly not going to deny it's existence for that reason. For most of what we know, we rely entirely on experiences other than our own.