How many people do you think we can actually fit on this planet, & will religion have anything positive to....?

The uneducated mes, who will mostly be theists, will expand in numbers. Those, who think they are doing someone a favour by thinking "The world is overpopulated, I will only have two children", when in fact they are just afraid of giving up some of their creature comforts, will dwindle in numbers. Large unpredictable events such as war, famine, disease and viruses will keep the population in check. It will cause suffering, but it will work.