I would write "Jesus's." Some prefer "Jesus'." "Jesus's" is always acceptable. Some authorities permit "Jesus' " as an accepted archaism. ("Jesus' " could also refer to something belonging to a...
The Desposyni's last Eldest Brother explains Jesus' real name, his surname and his "Lost Years" that are not included in the Bible (ages 13 to 29): http://www.thetruejesus.org/secret_writings.htm