Christians who fail in their service often don't understand why they fail. We'll be on this for a while.
A successful entrepreneur, who had started several successful small businesses, did a study on why new businesses fail. The owners would tell him why they had lost customers. But when he talked to customers who had stopped buying from those businesses, they gave different reasons.
When I started at a paper mill, my net worth was less than $1,000. Fourteen years later, I retired to Mexico, while my co-workers could not afford to leave. Twelve years later, most of them are still there. While the US stock market averages over 10% per year, most investors don't do that well, and many of them lose their money. Researching heavily, I could see what they were doing wrong and avoided those mistakes. But I also read that when their mistakes were explained to them, most of them refused to change.
Some people don't understand why they fail, even when it is proven to them. Why not?