That emblem is a depiction of St Christopher, and the small child he is bearing is the 'Christ child' who he is shown carrying across a dangerous stream.
Christopher means "Christ-bearer" which comes from the Greek Christos (Christ) and pherein (to bear) via the Latin Christophorus (Christbearer)
He is known as the patron saint of travellers, and lots of Catholics and Orthodox observers carry small St Christopher medals in their cars to protect them.
Now - why is it on an Alfa - most likely the owner put it on to protect his car. Although I guess it's possible that Alfa Romeo put it there since their main Milanese emblem does show a serpent swallowing a Muslim! So they clearly weren't too worried about being politically correct.
1967 Duetto 1600