One of the meanings of the word “world” as it is used in the New Testament is, “the ungodly multitude; the whole mass of men alienated from God, and therefore hostile to the cause of Christ.” Another meaning is, “the whole circle of earthly goods, endowments riches, advantages, pleasures, etc, which although hollow and frail and fleeting, stir desire, seduce from God and are obstacles to the cause of Christ.” (Both of these definitions are from Thayer’s Greek Lexicon)

This is what the Bible says about the “world” in this context.

"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. For all that is in the world, the lust of the flesh, and the lust of the eyes, and the pride of life, is not of the Father, but is of the world. And the world passeth away, and the lust thereof: but he that doeth the will of God abideth for ever." - 1 John 2:15-17 KJV

When we covenant with Jesus, our Heavenly Father, we turn our back on the things of this world and give our hearts to Him. We are baptized in His name Jesus for the remission of our sins, and have received the Holy Ghost, God’s gift of His Holy Spirit to those that covenant with Him.

"Hear, O Israel: The LORD our God is one LORD: And thou shalt love the LORD thy God with ALL thine heart, and with ALL thy soul, and with ALL thy might." - Deuteronomy 6:4-5 KJV (Capitals my emphasis)

God does not accept #2 position in our relationship with Him. We choose either to love the world and the pleasures of sin, or to love Jesus first of all.

"Ye adulterers and adulteresses, know ye not that the friendship of the world is enmity with God? whosoever therefore will be a friend of the world is the enemy of God." - James 4:4 KJV

When we covenanted with Jesus, we left the world behind us. Like Jesus, we are in the world but we are not of the world.

"They are not of the world, even as I am not of the world." - John 17:16 KJV

The word “world” is translated from another word in the New Testament that means, “period of time, age.” This includes the meaning, “men controlled by the thoughts and pursuits of this present time...conformably to the age to which this (wicked) world belongs...the devil, who rules the thoughts and deeds of the men of this age... (Thayer’s Greek Lexicon)

By our old sinful nature, which was disobedient to God, we once walked being blinded by the god of this world, the prince of the power of the air.

"Wherein in time past ye walked according to the course of this world, according to the prince of the power of the air, the spirit that now worketh in the children of disobedience:" - Ephesians 2:2 KJV

"In whom the god of this world hath blinded the minds of them which believe not, lest the light of the glorious gospel of Christ, who is the image of God, should shine unto them." - 2 Corinthians 4:4 KJV

By the gospel, we have been transformed. While we were once blind, now we see.

"And be not conformed to this world: but be ye transformed by the renewing of your mind, that ye may prove what is that good, and acceptable, and perfect, will of God." - Romans 12:2 KJV

Baptized in His name, and filled with His Spirit, we are now on the winning side with Jesus, our Heavenly Father and Creator of the universe.

"Ye are of God, little children, and have overcome them: because greater is he that is in you, than he that is in the world." - 1 John 4:4 KJV

By the gospel, we are born of God, born of water and of the Spirit, and are overcomers of this world.

"For whatsoever is born of God overcometh the world: and this is the victory that overcometh the world, even our faith." - 1 John 5:4 KJV

While we are still in this world, we do not have enemies that we wrestle in the physical sense; we wrestle in the spiritual, keeping the victory and interceding for others to be set free from the world, praying for them in the Spirit.

"For we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high places." - Ephesians 6:12 KJV

We say Goodbye to the world when we turn to Jesus. And one day, it may be very soon, it will be a final goodbye, as the songwriter said in the song, “Goodbye World Goodbye”. As the Bible says, “…And so shall we ever be with the Lord." 1 Thessalonians 4:16-17

Here’s the song with special guest appearance by the author of the song:

https://video.search.yahoo.com/search/video?fr=opensearch&p=Good-by+World+Good-by#id=4&vid=ea698ad616ae34a200d6a6dc973ee296&action=click