Right before He ascended to heaven, Jesus Christ gave us what is now called the "Great Commission", as found in Matthew 28:19-20:
Therefore go and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, and teaching them to obey everything I have commanded you. And surely I am with you always, to the very end of the age.That seems pretty straightforward - we are commanded to proclaim salvation through Jesus Christ throughout all the world. And certainly the Church has been engaged in that mission from the time of her inception in the First Century. Many have paid the ultimate price in preaching the Gospel, starting with Our Lord.
However, Pope Francis has told us on more than one occasion that proselytizing doesn't work. He has called it "nonsense."