So if your aim is to persevere in the Christian life and not be defeated by the wiles of the devil, then you must put on the armor described in these verses. This is how God means to keep us safe unto the day of salvation. Notice that we are not shod with the gospel. The gospel is the word of God and the word of God is our sword according to verse 17. We are not shod with the gospel.
Feet are for moving from one place to another.
If you put on shoes of readiness, then the idea would seem to be readiness to do what feet are for, namely moving. Let me show you two or three reasons why I think this is the right interpretation. Here we have a picture of the feet of people how are running to bring good news and the good news is good news of peace. Surely this is where Paul got his imagery. Here's another reason I think this is what Paul has in mind, and this is really interesting.