2 Corinthians 5:17 (ESV)

"If anyone is in Christ, he is a new creation. The old has passed away; behold the new has come."

There is no other perfect illustration for this part of scripture than the illustration of the 'Prince of Preachers', Charles Spurgeon. His illustration is about a hog and the two plates of food. We will suppose that there is a hog and there are two plates of food in front of us. 

On the right side is the finest food that you can freely imagine and on the left side is all but rotten garbage and trash. Then, if we let the hog loose, where do you think he will go? On what plate of food shall it plunged into? Of course, no matter how fine the food it is on the right side, the hog will still dive itself into the plate of rotten food because it is its nature... PIGS EAT TRASH! That's it!

But, if I have the power to change that pig into a new creature.. into a man (of course no one have that ability except God).. He will realize what he is doing and come into the senses that he is no longer a pig but a new creature. And when he realize that he is eating trash and rotten foods, he will vomit it and spit it, because he is no longer a hog but a new creature! So, instead of choosing the plate of rotten mess, he will now directly go to the finest food and act like a human does. 

Reflection:

Likewise, a true and genuine Christian is now dead to sin and alive to God. The course of his life is not now on the path of sin and unrighteousness rather, into good works and righteous deeds, bringing glory to God the Father through the Lord Jesus Christ.