...is you. Your bank account isn’t keeping you from being generous because generosity has nothing to do with how much you have or don’t have.
Your situation and circumstances aren’t keeping you from being generous because God has promised to take care of your needs (look at Luke 12:29-31 or Philippians 4:19 as reminders of this promise).
No, what’s keeping you from being generous today is your refusal to be generous. No one is keeping you from giving consistently other than you. No one is keeping you from giving sacrificially other than you. No one is keeping you from giving cheerfully other than you.
The good news in all of this is that God is not like you; he is anything but stingy. His generosity shows up in creation, is perpetuated every time his covenant love is renewed across the pages of history, is magnified most clearly in the life and death and new life of Jesus, and is on display in his affections towards you.
You can be generous today - because ‘you know the grace of our Lord Jesus Christ, that though he was rich, yet for your sake he became poor, so that you by his poverty might become rich.’ (2 Corinthians 8:9)
NOTE: For more on this, listen to last Sunday’s sermon on how we become generous.