If the principles of the spiritual life are misunderstood, there will often be neurotic reactions. Some Protestants felt all emotional movements were evil, which is why Protestant countries are more stiff than Catholic countries. The Council of Trent rejected the Protestant view, explaining that concupiscence is not sinful in itself. These embers of sin are left in the baptized and cannot harm those who do not consent to it. As to what Saint Paul calls a sin, the Council declared that the Church has never understood it as a sin, but that it comes from sin and inclines to sin.
Concupiscence is a disorder of the emotions and comes from original sin and leads to personal sin.
The emotions are good and are real. To deny them allows the devil to work.