Peter’s reaction is the standard human reaction, “Heaven preserve you, Lord. This (suffering and death) must not happen to you”.
Jesus uses the prophecy of his own grievous suffering and death (described as put to death) to teach his followers something that’s completely counter cultural. We just don’t think in these terms.
“… anyone who wants to save his life will lose it; but anyone who loses his life for my sake will find it.”
The use of “saving” here is interesting – it means keeping life for yourself, hoarding, accumulating, because you’re afraid to give it away, to give it to Christ.
“Saving your life” then means placing yourself and your own ‘kingdom’ at the centre of your existence which inevitably leads to materialism and consumerism. Most of us do this to some degree – herein lies the fundamental difference between the average Catholic (you and I) and someone like Padre Pio.
We do this because we want to be happy.. we’ve bought the belief that happiness is attained through consuming the material. But who told us that?
Actually, we must believe this in a society where the economy is “God” – although a false god.
The ultimate victory of this belief is to win the whole world – a point Jesus makes – but he then subverts the idea asking what good is it to win the whole world but ruin your life? He means ruin your eternal life; to possess everything the world can offer but have nowhere to go! But we don’t think like that because we’ve been conditioned to think that winning the whole world is life at its very best. But that’s not your life. Your life is your pulse!
Anyway, the inner dynamic is much the same; we give to receive…
However, Jesus is arguing that the secret to happiness is in placing not yourself and your own kingdom but rather Jesus Christ and his kingdom at the centre of your existence.
The inner dynamic remains; we give to receive which is what Jesus argues, “… anyone who loses his life for my sake will find it”. The loss here is to one way of life, a worldly way of life, but in return we enter into (find) the kingdom of God, the life of God, which is so much greater.
Indeed, only when a man can see something greater (when seduced as in the First Reading) will he begin to let go of what he already has…
We can use these terms to understand much about the Christian life including a vocation to the priesthood.