Catechism of the Catholic Church §2106 — excerpt
"Nobody may be forced to act against his convictions, nor is anyone to be restrained from acting in accordance with his conscience in religious matters in private or in public, alone or in association with others, within due limits."
This translation is under copyright, so only the cited words are quoted here. Follow the link for the full text. Translation: English translation of the Catechism of the Catholic Church, 2nd ed. (Libreria Editrice Vaticana), as posted at vatican.va.
Also cites: DH 2 # 1 · DH 2 # 2