The key to success has not Changed

 Read 1 Chronicles 18. 

Just because a person is right with God, prays to God, and is blessed by God does not mean that they are exempt from the battles of life. 

Coming out of chapter 17 where David enjoyed a wonderful encounter with the LORD, multiple wars then broke out.  However, in each case we read "And the LORD gave victory to David wherever he went." 

When a person's ways please the LORD everyone around them benefits.  The battles were not fought nor won by David alone.  Thousands of others were involved.  The proof of one's true motives is often revealed when the battle is over.  Notice how David behaved afterwards.  "So David reigned over all Israel, and he administered justice and equity to all his people."  He was a blessing to others as God had blessed him. 

It is a reminder of the LORD's instructions to Joshua.

"This Book of the Law shall not depart from your mouth, but you shall meditate on it day and night, so that you may be careful to do according to all that is written in it.  For then you will make your way prosperous, and then you will have good success."  (Joshua 1:8-9)