How come there are so many references to St. Joseph as the “foster father” of Jesus? Isn’t he the father of Jesus?
St. Joseph is often called the “foster father” of Jesus in order to emphasize that he is not Jesus’ biological father (cf. Matt. 1:18-25). As Jesus was conceived by the power of the Holy Spirit in the womb of the Virgin Mary, Joseph cannot be considered Jesus’ birth father.
However, so long as Jesus’ parentage is rightly understood, it is not wrong to refer to Joseph as Jesus’ father. Joseph acted as Jesus’ father in this world and was considered by Jesus’ contemporaries (cf. Matt. 13:55) and by the Virgin Mary herself (cf. Luke 2:48) to be Jesus’ father.