The answer
Although St. Mary and our Lord Jesus Christ knew that St. Joseph was not our Lord Jesus' biological father, he deserved all honor and respect having been His foster father. Before the whole community they lived in, St. Joseph was known as St. Mary's husband and our Lord Jesus' father otherwise it would have been very difficult at that time to explain the virginal birth of our Lord. St. Mary and our Lord Jesus rightfully gave St. Joseph this honorable position; for the great role he played in having to leave his country and escape to Egypt to save a Child who was not his own. Then, coming back to Galilee he raised him as his own. So it is not too much to address him as our Lord's father.Answered by His Eminence Metropolitan Youssef (opens in a new tab)