The Greatest Service that We Can Do Unto God

They that trust in the LORD shall be as mount Zion, which 
cannot be removed, but abideth for ever.
                                          Psalms 125:1

.....the greatest service that we can do unto God is to trust him.
For this is the nature of God to create all things of nothing. Therefore
he createth and bringeth forth in death, life; in darkness, light.  Now
to believe this is the essential nature and most special property of faith.
When God then seeth such a one as agreeth with his own nature, that
is, which believeth to find in danger help, in poverty riches, in sin
righteousness, and that for God’s own mercy’s sake in Christ alone,
him can God neither hate nor forsake.
                                                Martin Luther