Faith is Jesus is a lot like Soros' theory of reflexivity. By believing, your behavior changes. Was it the change in behavior due to psychology, or some supernatural spirit that effects the improvements seen later? And when good results come, do they also influence the beliefs to strengthen the effect?
Your point is well taken. In this country (USA) we are free to experiment with our belief systems, then move to whatever state, city and neighborhood we choose. And I hope you can see my point - that the results bear witness to the fruits of our thoughts, beliefs, and actions.
In my own case, 18 years of trying to make peace with my anger got nowhere. But the Lord wiped it all away and it has not come back for as many years.
And even Jesus told a parable about trading, which I am trying to live up to now. It made me realize how much of a coward I really am!