Often the prayers we say will sound something like:
'Lord, open hearts in advance of your gospel. Prepare people now so that later we will come across those upon whom your Spirit has worked.'
If this is how we think then we're basically conceiving of the gospel as a necessary instrument to salvation but it's not really at the heart of the action. The action happens in some prior (wordless) event. The gospel word merely comes as confirmation of a previous display of divine power - it's not the power itself.
On this view, the gospel is like a barcode gun.
We zap a hundred people and - glory! - we discover that five had been slipped the right barcode in advance.
The gospel here is confirmatory of a change that has happened elsewhere. As I've said, it reveals a prior power. It's not the power itself.
The gospel is like a magnum!
The gospel is the power of God for salvation (Romans 1:16). Proclaiming the good news is unleashing divine power. We fire off a hundred rounds of the gospel and a hundred people have felt the power of God - whether for their salvation or their greater condemnation.
The gospel does not merely confirm a prior mark placed on a person. The gospel makes the mark!
So as you go out into the world with the gospel, let this affect your confidence, your reverence and your prayerfulness: It's not a barcode gun you carry - it's a magnum.