Whatever ‘I’ am is somehow the portion of life that makes experience of the world unique to one person and not another. Life is the connection between the ‘whatever makes me me and not you’ and the power to change something in the world. If life is ‘will’ (the power to affect some form of change in the world), then death is the cessation of power. And if that is accurate of death, than to die to oneself or sacrifice one’s life for that of another is no less a material, concrete, actual death than anything else; it is perhaps a matter of degree or fullness of that death, but it cannot be relegated to some ‘spiritual’ realm or trivialized as not an actual death.
Miracles (literally, deeds of power) are then also not specialized outside of the realm of possible/material but are the particular acts of will that effect a change only through an assertion of power. To die to oneself and be alive in Christ is for the power you ‘have’ over the world to be controlled by the power of God to effect the salvation of the whole world; again not a ‘spiritual’ death and rebirth but a fundamental shift in whatever it is that makes ‘you’ you. Salvation comes through death because it is the final and complete surrender of all that made ‘me’ me in distinction or conflict with that power which is God’s in the world. Salvation is, then, the quintessential example of a miracle.