I don't know whether or not he's being a tightwad, but I do know he isn't looking at the way his church uses its money from God's point of view. God is pleased when we aren't interested only in ourselves and our needs, but are concerned also about the needs of others.
I couldn't help but think of how the early Christians might have answered your question. Most of them were very poor; some had even lost almost everything they owned because their families or friends turned against them when they became Christians. And yet when they heard about a famine that was affecting people in a distant part of the world, they gave generously to help them. So should we.
Remember: Jesus Christ left heaven's glory and sacrificed His life for our salvation. He did this out of love -- and He calls on us to have that same kind of love for others. Pray for your uncle -- and be an example to him by your own giving and concern.
We live in a very materialistic, self-centered age -- and even those of us who are Christians can be infected by its attitudes. But God calls us to love others just as much as we love ourselves -- and to show our love in concrete ways. The Bible says, "Whoever sows sparingly will also reap sparingly, and whoever sows generously will also reap generously.... God loves a cheerful giver" (2 Corinthians 9:6-7).