Matt 19 is pretty clear. Jesus answered His' disciples by telling them to forsake all their worldly things and they'd be rewarded with spiritual things. Jesus certainly didn't tell them to go and build mega-churches and keep the doors locked 5 days a week.
"but we are promised that God would open the windows of heaven and pour out blessings when we give tithes and offerings."
It seems as though you and CyberAnt (who quoted Deut 28) are hung up on the "conditional & temporal" promises God made solely to the nation of Israel. We are not Jews, we don't live in the covenant land, we're not under the condemnation of the law given to Moses, and we certainly have a perfect Priesthood compared to the Levites. (Heb 10:1-10)
The Israelites were not able to receive the promises/blessings because of their disobedience. What makes you think we would fare any better under the conditions of the old covenant? If you are trying to receive the blessings God promised Israel (by quoting Malachi) then you must also partake of the curses, too.
God gives us gifts and also blesses the work of our hands to multiply what we do.
"Matt 19 is pretty clear. Jesus answered His' disciples by telling them to forsake all their worldly things and they'd be rewarded with spiritual things. Jesus certainly didn't tell them to go and build mega-churches and keep the doors locked 5 days a week."
You can take any example to a ridiculous conclusion if you try hard enough.
Saying that God is only concerned with spiritual things is such a mistaken attitude. There are so many teachings in the OT and NT concerning money and how we will be blessed or cursed depending on how we handle it. I can cite those but I bet you are familiar with them already.
"We are not Jews, we don't live in the covenant land, we're not under the condemnation of the law given to Moses, and we certainly have a perfect Priesthood compared to the Levites. (Heb 10:1-10)"
Nope, we are not Jews. But we are ingrafted in the vine. And Jesus came to fulfill the Law, not to destroy it. We have a better covenant.
"The Israelites were not able to receive the promises/blessings because of their disobedience. "
Not true. They went through many periods where they rec'd the blessings because they were obedient. They lived by God's principles and prospered during those times. There are many examples of people who prospered because they followed God's laws of handling their finances. The times they were disobedient were the times where they were taken into captivity and they became a debtor nation.
"What makes you think we would fare any better under the conditions of the old covenant? "
We aren't, both as a nation and as individuals in this day right now. Look at the current crisis we are in. If people (and our leaders) had stayed true to biblical principles of not going into debt then we wouldn't be in this position now.
"If you are trying to receive the blessings God promised Israel (by quoting Malachi) then you must also partake of the curses, too."
As I said, Jesus came to fulfill the Law, and not one jot or tittle has been replaced. Right now we are suffering as a nation (and will suffer even more) because of us turning our back on those principles laid out in the OT. We have experienced the blessings in the past and right now we are enduring the curses.