I notice that most of the figures in the painting are looking to this seated figure. How we should identify him is an interesting question. Matthew 10:10 reads; Don't take a traveling bag for the road, or an extra shirt, sandals, or a walking stick, for the worker is worthy of his food. This may explain the bag and staff; an encumbrance tying the poor soul to this world? Alternatively, the cloak, staff and purse are the symbols of the philosopher, as on the Boscoreale cup. Originally these were associated with Cynicism, but the meaning expanded to include philosophers generally.
At any rate, the man is surrounded by other figures vying for his attention; Nike the goddess of Victory stands on a globe, offering him the world. Hermes is at his right ear, the god of commerce and trade, offering him security in wealth. Aphrodite is to his left (portrayed here with her girdle), offering pleasure; she gestures towards the bedroom and the richly furnished table. The child Eros is on hand as well, and offers Love.
In the center of the painting stands Jesus Christ, with Chalice and Host. To his right is Hercules, to his left is Achilles. Labor and Duty, perhaps? At the focal point in heaven is the Hebrew name of God, YHWH.
The left of the painting is obscure to me.