BUT. . .

 “O Moab, they weep for you!  The people of the god Chemosh are destroyed!  Your sons and your daughters have been taken away as captives.  But I will restore the fortunes of Moab in days to come.  I, the Lord, have spoken!”   (Jeremiah 48:  46-47, NLT)

The entire chapter of Jeremiah 48 speaks of the sin and destruction of Moab, except for the very last verse.  And, then there's a "but".  Restoration will come!

The Moabites were descendants of Lot through an incestuous relationship.  Lot's oldest daughter gave him wine, he became drunk, and she lay with him in order to preserve the family line (Genesis 19).  The Moabites led the Israelites into idolatry (Numbers 25).  Chemosh was their main god, and child sacrifice was an important part of worship (2 Kings 3).  They were also very prideful, and God cannot tolerate pride.  From the looks of all this, I would say that God had plenty of reasons to order the destruction of Moab.  

BUT, even though God destroys, He restores.  This passage of scripture doesn't tell when or how Moab was restored, BUT since God promised that He would, then it must come to pass.  What a merciful God!  We find this time and time again.  God will allow destruction to come, BUT then show His loving kindness and mercy.  Even in our own spiritual lives, hardships and trials will occur.  There may be difficulties that come as a direct result of our sinful behavior, BUT it doesn't mean that God does not love us.  He just allows those things to happen for His perfect will to be manifested in our lives.