Jesus called the people and his disciples to him and said,
"If anyone wants to be a follower of mine, let him renounce himself and take up his cross and follow me. For anyone who wants to save his life will lose it; but anyone who loses his life for my sake and for the sake of the gospel, will save it. What gain is it for anyone to win the whole world and forfeit his life? And indeed what any anyone offer in exchange for his life? for if anyone in this sinful and adulterours generation is ashamed of me and my words, the Son of man will also be ashamed of him when he comes in the glory of his Father with the holy angels." [Mk 8:34-38]
Jesus' invitation was entirely in keeping with the call-to-arms of any Jewish leader of his time who was determined to overthrow the rule of Rome. In fact the reference to the cross was a reminder of what would happen to the followers of a political messiah if they failed. To crush any thought of rebellion, the Romans would hang freedom-fighters on crosses along the main road out of town when they caught them. Though Jesus was a spiritual messiah, the threat to his followers would not be less.
The self-renunciation has nothing to do with a psychological self-image. It simply means putting aside what we want to do for what God wants to do, like Jesus did in the Garden of Gethsemene when he said: "Not my will but thine be done."
The invitation "follow me" was a call to a very distinctive relationship in the Jesus' time. It meant on the one hand that the follower, known as a disciple, would serve his master to such an extent that he would be indistinguishable from a slave. The one distinctive feature was that he would not minister to his master's feet. On the other hand , the disciple would learn the wisdom of his master and imitate him, so as to be able to inherit his spirit. The well-trained disciple would be a copy of his master. The Romans would have to kill all the disciples along with the leader, if they were to crush a rebellion.
The juxtaposed references to losing one's life for the sake of the gospel and winning the whole world puts Jesus' invitation in the context of the fight against evil. Satan wants to rule the world through his agents; Jesus wants his followers to overcome that rule. Our response to the invitation has global consequences.
Finally, there are the eternal consequences. Jesus issues his invitation with a view to his return in glory. It was this vision of the things-to-come that motivated Jesus' first followers as they would motivate any freedom-fighter to avoid the shame of letting his leader and comrades down.
This is the commitment the Church needs if we are going to set people free from sin and bring Humanity home to God.