This is something I started to experience once I became a non-theist. It is a joy without penalty or guilt, a joy that does not clash with any of my values.
When I went back home, and they found me truly happy in non-belief, my mom brought in the brainwasher who tried to induce guilt by telling me twice; once directly and next through my mom that he knew with his mind reading super powers that I was committing a sin knowingly. He tried to get me to confess it.
But you see, my conscience was so clear. I felt like Jesus in front of high priests. It was so clear and so joyful to be guiltless and full of confidence to know you are moral. I’ve never been capable of that feeling when I was a theist. I used to burdened by unnecessary shame, regret and fear by my imaginary Kim Il-sung in the sky judging my every thought and action.
I have come to realize that Happiness is possible only to a rational man, the man who desires nothing but rational goals, seeks nothing but rational values and finds his joy in nothing but rational actions.