Paul started the chapter wanting to pray for the Ephesians, but he digressed. The reason for his digression was the fact of his imprisonment which was paradoxical to the freedom and peace he wrote about in ch.2.
This is a paradox we struggle with. We know of the victory of the cross and the empty tomb. We find it hard to accept that the gospel - the "good news" - so often comes through broken people and in broken circumstances.
It is hard to accept that the same church that was responsible for the Crusades and the Inquisitions is still being used by God. It is difficult to accept that the people who lead us to Christ sometimes have feet of clay. It is confusing that coming to Christ can result in rejection by family or social circles. It's hard to understand that trouble, hardship and even imprisonment can happen to the children of God.
The so-called "prosperity gospel" (in its worst form) tells us that we are "kings kids" and that our wallets should be loaded, our circumstances peachy and our victories sure. But the real truth is that our Saviour was tougher than the nails. The early Christians retained their faith in spite of hardship. The real gospel isn't the absence of trouble - it is the hope and fortitude to overcome. Trouble doesn't thwart the gospel.
You and I should not be dismayed or discouraged at trouble. Jesus, our champion and hero, overcame a "perfect storm" of trouble and He will help us.
Paul sees his imprisonment as an opportunity for the Ephesians: he's stuck in prison and so baton goes to them! The gospel is unthwarted!!!