1. Almost all of God's promises to us are conditional: they require something from us in order to receive something from Him. I have seen people who did not understand this become angry with God when the promises did not "work" as they expected.
2. In a conversation with a friend this week about the often-heard phrase, "The Word works!", I said: "I agree--but with an important caveat: it "works" by understanding, not simply by knowledge."
I believe God made it so as a failsafe. Otherwise, a lot of people would be running around "using" Him and His Word to do or get a lot of things they should not be doing or getting.
"If you keep my laws and are careful to obey my commands, I will send the seasonal rains. The land will then yield its crops, and the trees will produce their fruit. Your threshing season will extend until the grape harvest, and your grape harvest will extend until it is time to plant grain again. You will eat your fill and live securely in your land. (Lev 26:3-5 NLT)