Humanism: An outlook or system of thought attaching prime importance to human rather than divine or supernatural matters. Humanist beliefs stress the potential value and goodness of human beings, emphasize common human needs, and seek solely rational ways of solving human problems.
Christianity: A faith-based belief system that attaches prime importance to divine or supernatural matters. Christian beliefs emphasize that all people are lost sinners in need of salvation through faith in Christ and that humanism is essentially a substitute religion replacing worship of God with worship of man.
Romans 1: 25
They exchanged the truth of God for a lie, and worshiped and served something created instead of the Creator, who is praised forever. Amen.
Jesus said to him, “Love the Lord your God with all your heart, and with all your soul, and with all your mind.”
This is the greatest and most important command. It is the foundation upon which our lives must be built. The allure of all other things in our lives melts away beneath the weight of the glory of undivided love toward God. If love toward God is truly the number one priority in our lives and valued above all other things then all our affections toward created things will be directed in a right manner.
Many men suppose that if they do not neglect their duty to their fellow men and if they are honest and upright in their dealings with others, that they are not guilty before God, as though it were less a crime to dishonour God than man and as though it were innocence to neglect the necessary salvation afforded us by our Maker and Redeemer. The apostle here shows that the wrath of God is equally revealed against the neglect of God as it is against positive iniquity; and that this is an offence of such consequence as to be placed first, and more deserving of Divine indignation than the neglect of our duties towards men. (Barnes’ Notes on the New Testament)
Romans 1:18-20 (HCSB)
18 For God’s wrath is revealed from heaven against all godlessness and unrighteousness of people who by their unrighteousness suppress the truth,
19 since what can be known about God is evident among them, because God has shown it to them.
20 For His invisible attributes, that is, His eternal power and divine nature, have been clearly seen since the creation of the world, being understood through what He has made. As a result, people are without excuse.