Actually the reason for this is because of a new doctrine developed in the Catholic Church since Vatican II: freedom of conscience.
According to this new theological concept, all human beings should be free to exercise their conscience as they see fit in all things religious, even when this means the freedom to reject religion.
The doctrine was developed partially due to the errors caused by the previous view. The previous doctrine (that all humans should not be free to choose religion outside the Church) contributed to the crimes of the Crusades, the Inquisition, and (though admittedly indirectly) contributed to the anti-Semitism that led to the Shoah. It also worked directly against the teachings of the canonized saints who were later recognized as doctors of the Church. Some of these were persecuted and even killed by the Church (i.e., St. Joan of Arc) when it turns out that their criticism of the Church was correct.
Therefore the Catholic Church now actively fights for freedom of religious and non-religious expression. Along with the JWs in Russia, the Catholic Church is working with several governments that are persecuting atheists, to find ways to stop the persecution. Pope Francis especially has been outspoken on not only assenting to this doctrine but practicing it and going one step further by forbidding proselytizing by any member of the Catholic Church. Under Francis, one may evangelize by example, but one may not proselytize to convince another that they are required to change and accept the Gospel.