By “coincidence,” the Son in this Trinity was played by Jim Caviezel, previously best known for portraying Jesus in Mel Gibson’s bloody The Passion of the Christ (2004).
(Spoiler Alert) The apostle Lionel Fusco (Kevin Chapman) was a corrupt cop who is redeemed by the Trinity and works with the Son to “save” others. In the final season, he becomes a “Doubting Thomas” whose faith is restored when he is accepted into the inner circle and learns the Truth. Another apostle, Officer Jocelyn "Joss" Carter (Taraji P. Henson) was “martyred” in the third season.
Samaritan, an evil copy of the Machine, was Satan.
Greek and Roman Mythology
However, one must step away from the Judeo-Christian tradition in explaining the other female roles. Samantha “Root” Groves (Amy Acker), who claimed to talk to the Machine, may correspond to the Oracle of Delphi, the priestess who delivered prophecies inspired by the Greek gods. After her death, the voice of Root and her persona were adopted by the Ghost in the Machine, thus elevating a woman to the Trinity.
Sameen Shaw (Sarah Shahi was a former ISA assassin now working for the Trinity. In a final message from the mortal Root, the Machine tells Shaw that if she were a “shape,” she was an arrow, perhaps a reference to the Roman hunting goddess Diana, who is often depicted with a bow and a quiver of arrows. Diana is sometimes accompanied by hunting gods; Shaw took custody of the dog Bear from Fusco.
In the last episode, the Son (Reese) gives his life to save the world from Satan (Samaritan). Finch, the Father, apparently survives. The Holy Ghost (Root) is resurrected. Heeding the Calling, Shaw is now the Daughter who replaces the Son in the Trinity. Thus, women become two-thirds of the Trinity.
The series aired on CBS, whose eye logo, like the Machine, seems to be ever watchful.
If culture is a shadow of reality, then perhaps Person of Interest reflected a true change in the divine forces that govern our world.