So it was their children, whom he raised up in their place, that Joshua circumcised. For they were uncircumcised, because they had not been circumcised on the way.
The entire generation of male Israelites were not circumcised. This was because they did not circumcise any of the male babies while in the wilderness and during the exodus. Yet God wanted them to continue with this tradition as a sign of the covenant with him that they were under as a nation.
Through the Old Testament there are various covenant renewal ceremonies. These are times when the people take special care to throw off their recent bad habits and remember the promises from god and the expectations for godly conduct that were established when these covenants were formed.
Today, the only thing which the church does that resembles a covenant renewal ceremony is the celebration of the lords supper. We have Easter, Christmas, and a few other memorial times of year, but these are not times where we remember the agreement which God has made with us to save us - they are memorials of events in the life of Jesus. Jesus used the word "covenant" to describe the cup he was drinking from at the last supper. Today, as we come to eat the bread and drink the wine, we should remember to put off our sinful habits and ensure that we eat and drink with confidence before God.