Chalam, yes this verse is used often to justify the tithe. I believe it is being taken out of context. First this is written to Ancient Israel. I would say the paying of the tithe was more like paying your income taxes than donating to your local church back then. Ancient Israel was a Theocracy. The tithe was used to support the government and the Levi class. The whole basis of Ancient Israel's government required everyone to do their part for the common defense and advance the nation. God was saying hey, if you don't pay your tithe (taxes) you are robbing me because you are taking away from your countrymen and brothers.
Contrast this with the book of Job, and what Jesus said about the tithe. As a Christian I have no choice but to critizize those who give only with the expectation of getting. Jesus didn't say the widow was dropping her two coins in because she was getting 20 back. He praised her offer as acceptable because it was from the heart. We could go all the way back to Cain and Able. God never appreciates an offering not from the heart. It can't be sincere if it is only to get something back. Even if you feel that God is blessing you like this, that is great. But to focus and teach it as doctrine is dangerous and a waste of time. Instead the focus should be on becoming more spiritual and getting closer to God and his love for us not just his material blessings.
