I am currently going through the Rite of Christian Initiation of Adults in order to join the Catholic Church. Do I need to confess the sins I committed before becoming Catholic?
The Catholic Church requires that one go to confession for any mortal (serious) sin one has committed after baptism. If the one entering the Church has never been baptized, there is no need to go to confession since the sacrament of baptism cleans the soul of all sin, regardless of its gravity. One could still do so in order to be more at peace with oneself. https://en.wikipedia.org/wiki/Baptism