Are we called to do “great things” for God? “No!” and “Yes!” In the incarnation God has already done the “Great Thing!” What we are called to do is obey, trust, seize the moment and do our best for God! The genius of that whole process is that God takes our little and makes it great. He takes our inadequate and makes it enough. The Multiplier of seed and bread gets the credit. “Great” belongs to God and modifies Him and His works and not me and my works.
“Now He who supplies seed to the sower and bread for food will supply and multiply your seed for sowing and increase the harvest of your righteousness; you will be enriched in everything for all liberality, which through us is producing thanksgiving to God. For the ministry of this service is not only fully supplying the needs of the saints, but is also overflowing through many thanksgivings to God” 2 Corinthians 9:10-12 (NASB).