In Ephesians, Paul refers to faith as a shield. We know various types of shield, the kite shield popular among medieval Knights (especially in movies), the sci-fi force-field often referred to as a shield as well as the shields which would have been known of at the time. The Israelites in the past would have used simple round shields or bucklers to provide some basic protection for one individual, however in the time when Ephesians was written, they would have been familiar with the Greek phalanx use of shields which the Roman legions improved upon with various group shield formations probably using the Roman tower shield. Each legionnaire would use his large shield to protect not only himself but also his comrades next to him and the group would work together as a whole to protect the whole group. We also see some similar tactics by the dwarven army in PJ’s version of The Battle Of Five Armies, and it looks awesome.
Considering how the Bible talks about unity and the church working together as one body, our faith should probably be cooperative as well as individual.