Judas Iscariot was (possibly) a member of the Sicarii, a group of "dagger men," known for their covert assassinations in an attempt to overthrow the Roman occupation of Judea.
Simon the Zealot was, well, a Zealot, a political group also wanting the violent overthrow of Rome.
Simon, Andrew, James, and John were fisherman from the city of Capernaum.
Levi Matthew was a tax collector, also from Capernaum. Jews hated tax collectors–they were collaborating with the occupying Roman force, taking working people's money. Simon, Andrew, James, and John would have especially hated Levi because he was their tax collector. Judas and Simon would have seen him as a public enemy.
And Jesus called each of them his friends and disciples. They traveled together, ate together, lodged together, went on retreats together.
If they could overcome their political differences to follow Jesus, maybe we can too?