The birthday of the "sun god" which was on 25 December became the birthday of the "Son of God" if you also believed that Jesus was born on 25 December.
Tswalo ya mora "modingwana wa letsatsi" eleng ka tsatsi la 25 Tshitwe "Mora wa Modimo"haeba o dumela hore Jesu otswetswe ka 25 Tshitwe o lahlehile.