As followers of Christ, we are called and empowered to worship God in all aspects of our lives. The Bible says In Luke 12:34, "For where your treasure is, there will your heart be also."  What we do with our money is an indication of what our hearts are after.  

Generosity is a form of worship.  We can express our devotion and gratitude to God through our tithes and offerings which are from the blessings that God has placed in our hands.