He brought them forth also with silver and gold: and there was not one feeble person among their tribes.
 Egypt was glad when they departed: for the fear of them fell upon them.
The final plague on Egypt was the death of the firstborn child of everyone who refused to trust in God. The firstborn represented the strength of a family. In the Egyptian mindset, Pharaoh and his firstborn son claimed to have the status of deity. Why do we have this last plague emphasized here?
Most nonbelievers respect the concept of "family" and caring about their children. God wanted to demonstrate He and He alone is in charge of how we deal with our families. This plague shows He is greater than our ability to produce children. Apparently this plague is what it took to get the Egyptians to finally say, ‘OK, that is enough. You Israelites, get out of here and take our gold with you’. It took the understanding that God is in control of life itself, for the Egyptians to let His people (Israelites) be separated from the Egyptians.
However, it is interesting to think about the fact that the Egyptians still refused to worship the God of the Israelites despite the damage and death. This alone shows the power that the “world” has over nonbelievers. To put it another way, many people still refuse to turn their hearts over to God because they don’t want to change their lifestyle. That is the great message being taught about the Egyptian people and about all people who refuse to trust in the God of the Bible.
By way of application, we must not merely think about the ancient Egyptians. This is also about knowing God has called us to be separate (in terms of thinking) from nonbelievers.