1 Corinthians 4:2 …moreover, it is required of stewards that one be found trustworthy. NASB
Faithfulness should be one of the leading characteristics of someone who serves God. “Well done, thou good and faithful servant…”  is the commendation that every believer should desire to hear. The New American Standard translates this word as ‘trustworthy.’ Trustworthy servants can always be counted on to do their job.
We should note that Paul refers to us as ‘stewards.’ What is a steward? The underlying thought behind this word is management. The most basic definition of steward is someone who is the manager of a household. Warren Wiersbe defines a steward as – “a servant who manages everything for his master, but who himself owns nothing.” Scripture teaches us that God has entrusted to each and every one of us a portion of His grace for us to manage for His glory. 
Albert Barnes gives us some important reasons for being faithful stewards. I will paraphrase these principles for our understanding:
We have been appointed by Christ
Jesus said, “You did not choose Me but I chose you, and appointed you that you would go and bear fruit…”  Whether our task is to teach a Sunday School class or care for someone in need, our assignment is from the Lord.
We will one day answer to Christ
The Bible says that each of us will one day give an account to the Lord of how we have lived our Christian life. 
Our assignment is very honorable
Though the Bible often refers to us as servants and stewards, we must never forget that what has been entrusted to us is a portion of God’s kingdom. Someone’s assignment may be a few rowdy kids in a fourth grade Sunday School class, yet those kids are very important to God. Their spirituality has been entrusted to that teacher’s care.
God’s glory should always be our goal
Recently I read these words from the book of Romans – “For from him and through him and for him are all things. To him be the glory forever! Amen”  Every task we are given has come to us from God. All the energy we need in order to accomplish our tasks will come to us by His Spirit. And every accomplishment we achieve will be for His glory.
 Matthew 25:21
 1 Peter 4:10
 John 15:16
 Romans 14:12
 Romans 11:36