As usual, the preacher is clever, and the thoughts are not heretical, but when we give the spiritual reasons why God did something, AND with a Bible text where God does not tell us why he did something, we are adding to God's Word. That is rather serious I think.
Note:
Revelation 22:18 For I testify unto every man that heareth the words of the prophecy of this book, If any man shall add unto these things, God shall add unto him the plagues that are written in this book:
19 And if any man shall take away from the words of the book of this prophecy, God shall take away his part out of the book of life, and out of the holy city, and from the things which are written in this book.
Phil Johnson needs to consider the consequences of telling God what he meant in the Bible.