"Now thanks be to God who always leads us in triumph in Christ . . . "
How is it that God *"always"* leads us in triumph in Christ? After all, don't we often fail; and aren't our lives many times filled with stress, confusion, and uncertainty? Answer: yes, they are; but this in no way negates the inevitable success of the children of God, as they are now in Christ, by faith.
The principle here is that it is your *faith* that is your victory, (even as 1 Jn. 5:4b rather explicitly states). Since you have Christ, by faith--nothing can conquer you. If your sins are forgiven, and you have a right standing with God, through the imputed righteousness of Christ (apprehended by faith alone)--then what can defeat you? Nothing.
[Puritan quote of the day: "Beware you do not lose your God in the crowd and hurry of earthly business." --John Flavel, in "The Mystery of Providence"]