Consider the accusation of James concerning the illicit love affair with the world as stated in the following paraphrase: "You [are like] unfaithful wives [having illicit love affairs with the world and breaking your marriage vow to God]! Do you not know that being the world's friend is being God's enemy? So whoever chooses to be a friend of the world takes his stand as an enemy of God."(James 4:4, Amplified Bible).
Being a friend of the world indicates that the person agrees with the values of the world system. The Old Testament Prophet Amos asked, "Can two walk together, except they be agreed?" (Amos 3:3).
The believer who is able to be in agreement with this evil world system is woefully out of fellowship with Almighty God, who saved him from the penalty and power of sin.
If a person has a consistently worldly life-style, it is a clear signal that he has never trusted Jesus Christ as his personal Saviour.
On the other hand, there are believers who are out of fellowship with the Lord and who are worldly for a time. Perhaps this is because many want Christ as Saviour but not as Lord.
They want the assurance and peace of knowing that they are saved from eternal condemnation, but they also want to live to please themselves rather than letting Christ be the Master of their lives.
"Love not the world, neither the things that are in the world. If any man love the world, the love of the Father is not in him" (1 John 2:15).