The "Sons of Anarchy" star got suited up Monday for a visit to St. Francis de Sales Catholic Church in Sherman Oaks ... for the baptism of the son of Ryan and Jennifer Betts Conroy.

Charlie's now Jack's godfather, and it's not the first time he's played a pivotal role in the couple's life.

Charlie first introduced the couple and even played best man at their wedding back in 2013. Based on the pic ... it looks like he's already got the new role down.