How is the cult of Osiris significant for understanding the world of Paul?

Worship of hellenized Egyptian deities was common in Northern Greece, especially Thessaloniki, whose main temple complex was for Egyptian deities. These is also a temple to Egyptian gods in Philippi.

Some make the claim that Christianity inherited its myths about resurrection from the story of Osiris. The Museum in Thessaloniki gives the basic story:

Seth killed and dismembered Orisis.  He then placed his remains in a coffin which he threw into the Nile. After some time, Isis found the remains of the body; the gods were impressed by her actions and resurrected her husband.

As is the case with Dionysos, all sorts of people draw connections between Jesus and Osiris.

How is Jesus different than Osiris?

Osiris never lived as a human with other humans.  Jesus lived as a human, fed and cured people.

Osiris was killed by another God; Jesus was killed by other humans, betrayed and abandoned by his followers.

Osiris never knew he would be resurrected; Jesus did. Indeed, while alive Jesus tells his followers:

Jesus said to her, "I am the resurrection and the life. Those who believe in me, even though they die, will live, and everyone who lives and believes in me will never die. (Gospel of John, chapter 11:25-26)

It was the faithfulness of Osiris' wife (she found all the pieces of his body) that pleased the gods enough to allow Osiris to be reborn; Jesus did not require the merit or actions of another to warrant his resurrection.

Osiris never saw his death as a sacrifice or victory for humanity, Jesus did. Indeed, Osiris worshippers would mourn and celebrate his suffering and death. However, they mourned for him. For Christians, the suffering and death of Jesus is more difficult and challenging because we acknowledge that his death and suffering were consciously for us.

Osiris, after his resurrection, became relegated to the underworld. Jesus took on human flesh out of his own will and dwelt among us.

Osiris stands as the gatekeeper to paradise. Jesus does not simply open the doors to heaven for us, but will come again to recreate a new heaven and new earth.  

To summarize, Osiris had neither the intent to redeem humanity nor the world.  He suffers neither with us nor for us; he resurrects neither himself nor us.