But seek the welfare of the city where I have sent you into exile, and pray to the LORD on its behalf, for in its welfare you will find your welfare.
In this command to the Babylonian exiles, God is giving instruction on how His people were to relate to a pagan culture. He did not want them retreating from the culture. That would not have been acceptable. Instead, God encourages them to settle in, live their lives, create households, have children and grandchildren, plant gardens, and make Babylon their home as much as is possible. After all, they would be there for 70 years.
They were to be a people who benefited the culture. They were to be the best residents of Babylon that the city had ever seen. They were to seek its welfare, for as Babylon thrived, so would their families. This then is the opposite of a cultural retreat. This is engagement with the city at all levels possible.
Now I know this is a very specific promise given to the Jews in a narrow point of their history. But I find in its principles thoughts for examining my own relationship with my culture. All my life the fundamentalist/evangelical sub-Christianity from my youth has sternly cautioned me to always retreat from my world. Its voice is always in my head, even today. And from childhood I have done so. My life has been defined no so much by what I was, but by what I wasn't and by what I didn't do. And it made a legalistic hermit of me.
I believe that if Christianity is going to advance it must engage culture with an exilic attitude. It must evangelize the culture by being part of the culture. I must seek the welfare of the city, with the gospel message clearly in hand, knowing and participating in the life of my world in a Christian way.