We are not promised that we will prosper just because we are Christians. We go through trials and tribulations just like everyone else. Look at Paul. Do you think he was any less of a Christian because of the hardships he endured?
Besides, you preach a false gospel, which some may not know about you just based on an isolated comment, so....
Actually I was reading in Deuteronomy Chapter 28 the other day and darned if I didn't come by a bunch of passages that clearly teach that if you "hearken diligently unto the voice of the LORD thy God, to observe and to do all his commandments which I command thee this day" then he will prosper you in all that you do.
It is later culminated in Deuteronomy 29:9 "Keep therefore the words of this covenant, and do them, that ye may prosper in all that ye do."
I don't think you can make the claim that if you are a Christian you are not promised that you will prosper. Indeed, it does appear scriptural that if you are a committed Christian and you are hearkening the voice of the Lord, then you will prosper in all that you do. That does seems to be a promise. While "prosper" does not necessarily mean monetary comfort or excess, a reading of Deuteronomy Chapter 28 and 29 does seem to make a pretty good case that God is truly anxious to prosper his people.
I don't know much about Osteen, but I suspect that if he claims that Christians will be blessed with pecuniary riches if only they ask, then IMO he takes this passage and others a bit too far. Quite a bit. But nevertheless it does appear that if we are not prospering in all that we do, then there may be a problem.