Reading CS Lewis' Mere Christianity, I came across another one of those quotes I had heard before, but never located. It's in a chapter titled 'Good Infection', and is really talking about the nature of the connection between us and God.
Here is the quote:
"Good things as well as bad, you know, are caught by a kind of infection. If you want to get warm you must stand near the fire. If you want to be wet you must get into the water. If you want joy, power, peace, eternal life, you must get close to, or even into, the thing that has them. They are not a sort of prizes which God could, if He chose, just hand out to anyone. They are a great fountain of energy and beauty spurting up at the very centre of reality. If you are close to it, the spray will wet you; if you are not, you will remain dry. Once a man is united to God, how could he not live forever? Once a man is separated from God, what could he do but wither and die?"
This, I think, is brilliant. It highlights the 'intrinsic' character of salvation, as opposed to an 'extrinsic' version - intrinsic to God that is. What do I mean?
Lewis highlights the fact that salvation and all its blessings are not somehow separable from God, as though you could have the blessings without having God.
On the one hand, this helps us understand what Paul (especially) means by "union with Christ". Our connection with Christ is not like the way we connect with a supplier, where a buyer pays something, and gets something in return. It's not only that we could never 'pay' God for salvation - it always comes to us as a gift, because of the price that Jesus paid - but also that there is no necessary relation between the supplier and the item that is supplied - it could be anything! Whereas what Lewis is pointing out is that what God gives us is nothing other - and nothing less than - himself! Hence, salvation could never keep God at a distance, as so many unbelievers think, who see themselves as "going to heaven" but have nothing at all to do with God.
On the other hand, it also helps us to understand why condemnation is not the arbitrary withholding of a "prize" from people who don't meet the selection criteria. To keep oneself from God is necessarily to keep oneself from the blessings of salvation, because salvation is nothing other - and nothing less - than the blessing of God's glory present and powerful for you.
Why does this matter? I suspect that many unbelievers in our post-Christian but still Christian hung-over context believe in God and salvation (at least, that's what the census says), but see salvation precisely like a prize, in the way that Lewis speaks about. And when we speak about salvation without clarifying its intrinsic character, we are heard to be saying, 'God is a prize giver, and you need to meet the criteria'. What happens then is an argument about the criteria - and many unbelievers are simply offended when you try to tell them they don't meet the criteria.
What Lewis helps us to see - and this is part of the whole contextualisation challenge - is that the problem here lies with the way the issue is framed in the first place. Salvation is not a prize, it is a 'good infection'.