The Gospel of Jesus Christ was foreordained by God from the beginning of time:
.......the Lamb slain from the foundation of the world (Revelation 13:8).
He knew one day He would reveal himself as Jesus Christ as the express image of God,
God, who at sundry times and in divers manners spake in time past unto the fathers by the prophets, Hath in these last days spoken unto us by his Son, whom he hath appointed heir of all things, by whom also he made the worlds; Who being the brightness of his glory, and the express image of his person, and upholding all things by the word of his power, when he had by himself purged our sins, sat down on the right hand of the Majesty on high (Hebrews 1:1-3).
coming to earth in flesh to die on the cross, to be buried and to rise from the dead giving us this precious gospel of Jesus Christ that the Apostle Paul describes in 1 Corinthians:
Moreover, brethren, I declare unto you the gospel which I preached unto you, which also ye have received, and wherein ye stand; By which also ye are saved, if ye keep in memory what I preached unto you, unless ye have believed in vain. For I delivered unto you first of all that which I also received, how that Christ died for our sins according to the scriptures; And that he was buried, and that he rose again the third day according to the scriptures (1 Corinthians 15:1-4).
This is the love of God that the Apostle John describes:
Hereby perceive we the love of God, because he laid down his life for us: and we ought to lay down our lives for the brethren (1 John 3:16).
In this was manifested the love of God toward us, because that God sent his only begotten Son into the world, that we might live through him (1 John 4:19).
For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life (John 3:16).
There are scriptures that describe the necessity of obeying the gospel if you want to go to heaven. The Apostle Peter wrote,
Yet if anyone suffers as a Christian, let him not be ashamed, but let him glorify God in that name. For it is time for judgment to begin at the household of God; and if it begins with us, what will be the outcome for those who do not obey the gospel of God? And If the righteous is scarcely saved, what will become of the ungodly and the sinner (1 Peter 4:16-18 ESV)?
and the Apostle Paul equates not knowing God to not obeying the gospel, resulting in an utterly avoidable but tragic ending:
And to you who are troubled rest with us, when the Lord Jesus shall be revealed from heaven with his mighty angels, In flaming fire taking vengeance on them that know not God, and that obey not the gospel of our Lord Jesus Christ: Who shall be punished with everlasting destruction from the presence of the Lord, and from the glory of his power (2 Thessalonians 1:7-8).
From these scriptures, it is clear that the Gospel of Jesus Christ must be obeyed to get to heaven, so why would anybody not do this? The primary reason is that the religious world has confused so many lost souls about what it means to obey the Gospel of Jesus Christ, i.e. how does one die, how is one buried and how does one rise again. The page "Do you want to go to heaven?" (click here or image below) clearly explains the Biblical truth of obeying the precious and loving gospel.