“Pastor Winters, would you be willing to give an invocation at our next event?” The first time that I heard this phraseology I thought it was a little silly. “Sure, that’s easy enough,” I though to myself, “I just say ‘In the Name of the Father and of the Son and of the Holy Spirit, Amen.'” Now of course the people who were asking for that were looking for more of a small devotional or prayer – not just me saying the Name of the Triune God. But that is what we as Lutherans call, “the invocation,” and every Lutheran worship starts with one. 
Invocation is literally, the act of calling. “Vocation” means “calling” and the preposition “in” means to “call in”. In the Church perhaps it would be better to talk about “calling forth”. We start our worship service with the words, “In the Name of….” which is interesting. It is not perhaps what we would think it would be. It is not an “invocation” that “calls God” but rather, it recognizes who we are called and how we are called. The invocation is the words of our Baptisms, and the words of our Baptisms are the words of Jesus who said, “go and make disciples, baptizing them in the Name of the Father, and of the Son, and of the Holy Spirit.” (Matthew 28)
Instead of our invocation being something that calls God from the mystic beyond of eternity, our invocation is rather like invoking a rule. In legal parlance, “invoking the rule” means to invoke a special rule about sequestration of a witness – usually to protect someone’s rights. That’s more of what we’re doing in our invocation. We are invoking the rule of our Baptisms, we are calling out for the normal rules of God’s righteousness to be held at bay for just long enough so that we can receive His forgiveness and love, and then be sent out again.
That rule is the rule of Christ’s love for us. It is the rule that we need to invoke every day. Let’s invoke the rule.