Francis Pieper was a theologian of the Lutheran Church-Missouri Synod who wrote Christian Dogmatics, the primary textbook of our church body. In it, he accurately summarizes our beliefs and teachings. Under the subtitle of “the Number of Religions in the World” he concludes,

“Therefore the true and only religion
and the true and only worship is this,
that one believes the forgiveness of sins,
which God gives graciously and freely, without subsequent or previous good works, from pure mercy,
just as He freely gives the light of the sun  and all other good things.
Believing in this good God,
Who bestows His blessings graciously and freely,
is the true religion and the righteousness.”