All people are born dead in their trespasses and sins. (Ephesians 2:1; Colossians 2:13) This condition of spiritual death also means that each person, though desperate for fulfillment that can only be satisfied in God, cannot come to God, know God, or even seek Him. Because of this, they pursue fulfillment from everything around them. The number one method of doing this is via the flesh. The flesh is all about self and self-gratification. The problem with this is that nothing works for very long, including religiosity.
Genuine Christians are regenerate. (Titus 3:5) That means that they are new creations. (2 Corinthians 5:17) That means that the old things have passed away and all things have become new.
17 Therefore if anyone is in Christ, he is a new creature; the old things passed away; behold, new things have come. 2 Corinthians 5:17 (NASB)
The Greek Interlinear (word for word from the Greek) version of this verse is, “So that if anyone is in Christ, that one is a new creation; the old things have passed away; behold all things have become new!” The words in italics are not in the original text. This is a remarkable statement. The word “therefore” or “So that” ties this verse back to v16. Here it is.