To espouse our confessions by proof-texting might suggest that some passages support doctrine, while others do not. The selectiveness of proof-texting encourages us to imagine that God reveals himself in hidden tidbits of Scripture. The Scriptures are overflowing with Christ and his doctrine. We fail to see this truly awesome reality because of the blindness caused by our sin. A better approach is to read and hear the words of Jesus in order that we might see the totality of what he does for us now throughout the entirety of the Scriptures.
Lutheran doctrinal writings bear the name "confessions" because we confess Christ’s doctrine – not ours. Doctrine is not made up of abstracted and distinct "theories" or "disciplines." Rather, Christ is our high priest, chief liturgist, and sacrificial Lamb of God. We confess that He is Lord and what He has done. We do not speculate beyond what the Lord has given us through His Word. All that he has done and is doing is "for us." For these reasons our confessions are considered ‘corpus doctrinae’ - given that it is a single statement that is anchored in Christ’s teachings, death, and resurrection.