34 Think not that I am come to send peace on earth: I came not to send peace, but a sword.
35 For I am come to set a man at variance against his father, and the daughter against her mother, and the daughter in law against her mother in law.
36 And a man's foes shall be they of his own household.
When we're talking about the world, we're talking about a system. We're talking about the philosophies embraced by the world and the tools they use for pursuing increase in the substance of that system. God has authorized the system of the world but has not sanctified it for faith.
The beasts of the field live by instinct to adapt to the environment they find themselves in but by faith in Christ, we are made able to stand upright and enter into a new environment provided by God for faith in Christ.
This new environment is also a system with knowledge and tools provided for increasing in the substance of that system but you cannot use both systems for building. If you choose both, you have chosen the world and are at enmity with God. If you choose the authorized and sanctified system provided by God, you will become an offense to those who are building and increasing in the system of the world. Thus, faith in Christ is enmity with Man.
The angels announced peace on earth at the coming of Christ and this will be fulfilled at the beginning of His 1000 year millennial reign... but first the righteous will be taken up by Him and He shall pour out His wrath for 7 years of tribulation. Those who forsake suffering in Christ now shall suffer needlessly without reward.
Learn about the Covenant Care of Christ: http://www.s8wministries.org/general.php?id=15
Study to show yourself approved: http://www.apostlejohnwelty.com/2012/02/study-to-show-yourself-approved.html
Seek first His Kingdom and Righteousness: http://www.apostlejohnwelty.com/2012/12/seek-first-his-kingdom-and-righteousness.html