The rule of law says that if you perform Action A, then Action B will follow. If you throw something off a cliff, it will fall toward the earth until something stops it. And so we are taught that, in the spiritual realm, putting something into motion such as "sowing a spiritual seed" is a guarantee that "your seed with multiply."
Jesus said, "Give, and it shall be given unto you; good measure, pressed down, and shaken together, and running over, shall men give into your bosom." (Luke 6:38) How did we Christians come to believe these words mean, when I give money, God is obligated to ensure that even more money than I gave will be returned to me?"
I've come to the conclusion that, while God doesn't change, His faithfulness and consistency doesn't imply He's simple. "A" doesn't always equal "B."
Don't mistake what I'm saying. God does indeed desire to give good gifts to his children. Unexpected funds do sometimes show up right when we need it. We can tell a blessing when we receive one and are suitably grateful.
But recall, in the Bible, how during Jesus' ministry on earth, not all were healed. The stories of Jesus' earthly ministry were diverse, and not a simple matter of "You giving something (alms, faith, righteousness) and God gives something back (blessings, money, property).
The woman who touched the hem of Jesus' garment was told her faith had made her whole. The centurion's servant was healed because of the centurions' faith, not his own. Some, like the man at the pool of Bethesda, seemed not to do anything specific to merit healing at all. In fact, after he received his healing this man had no idea who he had even received healing from!
Here's the problem. We prefer God's blessings on the merit system, because the merit system lets us, not God, put the blessing in motion. We want to dictate our own blessing. When in truth, it is with faith, not formula, that we should approach God with our needs.