When we read scripture we see a lot of references to war, fighting, struggles, wrestling. This is not a coincidence. Paul is using these references in order that the people to whom he is writing can understand his ideas in a context they recognize. This is the time of Pax Romana. Propaganda Rome put out in order to maintain peace. It means the peace of Rome. This was Rome’s theme to the nations they conquered declaring they were bringing peace to the world. But this peace was through war. And this war needed soldiers. If a person who was a slave wanted to be free, or someone wanted to be a citizen of Rome (which was highly coveted), he could join the army and pledge pistis or fides. The first word is what we translate from the New Testament as faith.
When a soldier joined the legion he would pledge faithfulness to his commander to do all that he commanded because he believed in the pax romana and that his commander knew how to achieve this. Paul used this idea to convey what it means to serve in the army of God.
However, faith goes much deeper than this reference. Paul, James, and others have said, faith was revealed in Abraham along with many others in scripture (Heb 11). Faith is a trust in what God has said would happen, has happened or will happen. Faith is a recognition of what may not be seen presently still has valid evidence that it will be accomplished (Heb 11). I think that’s why Paul doubled down on the faith of the soldier. We serve the God of all creation active in his kingdom fighting against the schemes of self, the world, and Satan. And though it may not be against blood and flesh, the battle is very real. But as we submit on bended knee and offer fealty to the king of all kings we recognize that when this war is over (in our perspective because the ultimate battle has already been won in Christ!!!) the Peace of God will reign and we will be able to put down our armor and weapons and enjoy the freedom of what it means to be a citizen of the Kingdom of God and heaven. Have you pledged faith to King Jesus?