As Christianity became popular, Rome started to free slaves. Later Rome was no longer a society based on slavery, rather early feudalism. Rome was also short on

As Christianity became popular, Rome started to free slaves. Later Rome was no longer a society based on slavery, rather early feudalism. Rome was also short on population after multiple plagues and needed to focus more on food production, rather than having enough manpower to industrialize. After all, they couldn't even put up armies in the size they needed. So at the time they could afford it, they were expanding or fighting civil wars, later they were scrambling to hold it together.