Can a Christian demand that God give them material things?
No. A believer cannot demand material things from God. Scripture says God is not tight, but He is not obligated to give them on demand. If He graciously chooses to bless someone with material things, that is acceptable only when spiritual priorities come first, with affection set on things above.
Les explains that Colossians 3 tells believers who have been risen with Christ to seek those things which are above, where Christ sits at the right hand of God. They are to set their affection on things above, not on things on the earth. This echoes Jesus' words to seek first the Kingdom of Heaven, and then all these things can be added. Les notes there is nothing wrong with material things if priorities are right; things become wrong only when they are more important than spiritual matters. God is not tight, but believers cannot demand material things from Him. If God in grace sees fit to bless them with things, that is fine as long as those things remain in the right order of priority.