In this case, my wife seems to believe and except the concept of predestination, but doesn't understand how that would include things like the colour of the socks we choose. She might not have a problem for a specific purpose in mind in order to bring a plan of God's to fruition.
1. Predestination is typically understood as God's determination and election of a specific number of sinners to be saved in Christ. Perhaps she is confusing predestination with foreordination or decree(s) of God?
2. Foreordination or the decree(s) of God encompasses EVERYTHING which God determined to come to pass out of nothing. In short, whatever exists had a beginning which was created by God according to His will. Thus EVERYTHING has a purpose. There is no such word or concept as extraneous with God.

Remember, even EVERY single hair on a person's head has been numbered, (Matt 10:29,30) i.e., determined by God from all eternity.
Another way of putting all this is EVERYTHING that God has decreed/determined/foreordained from eternity is for the display of His own glory. Would it be proper to relegate ANYTHING to the "unimportant" bin?
