Luke 11:23 He who is not with Me is against Me, and he who does not gather with Me scatters.
The above that Jesus said also shows us we live in this present evil age.
The unsaved are aligned with devil and are against Christ. They may claim God as their father, but this is a lie.
They are at enmity with God and Christ and follow the wicked devil and desire to do the devil's will.
The devil for example does not want people getting saved, or putting Christian morality into the world. It can seem oh so peaceful and nice their ungodly antichrist ways.
Paul speaking of the church says it also this way about the unbelieving world that they are children of the coming wrath of God that will burn this world with an all consuming destructive fire and then God will give us a new earth.
Ephesians 2 New King James Version
1 And you He made alive, who were dead in trespasses and sins, 2 in which you once walked according to the course of this world, according to the prince of the power of the air, the spirit who now works in the sons of disobedience, 3 among whom also we all once conducted ourselves in the lusts of our flesh, fulfilling the desires of the flesh and of the mind, and were by nature children of wrath, just as the others.
4 But God, who is rich in mercy, because of His great love with which He loved us, 5 even when we were dead in trespasses, made us alive together with Christ (by grace you have been saved),