William James once claimed, "If your heart does not want a world of moral reality, your head will assuredly never make you believe in one."
There ARE a great many atheists who do not want a world of normative moral reality. Thankfully many do not fit in that category though they maintain that a person can live a good moral life without God in the picture.
The elephant in the room, of course, is that while atheists benefit from a residual Imago Dei, they have not been spiritually renewed by the Holy Spirit as "new creatures in Christ" with a new "heart of flesh" that earnestly desires God's holiness.
So in addition to whatever morality they choose to ascribe to not being good enough to meet God's HOLY standard, they are attempting sanctification in their spiritually dead state which is intended to be accomplished in a spiritually alive state.
Consider the following:
"The term 'new birth' embraces two Greek expressions found in the Gospels: palingenesia (Mt 19:28; variously translated as 'the renewal of all things' [NIV], 'the world that is to be' [NEB], 'the new world' [RSV]) and gennēthēnai anōthen (Jn 3:3, 7; 'to be born again” or 'to be born from above').
These two expressions point to the saving activity of God in imparting spiritual life to his people and in restoring all of creation. This activity has both present and eschatological dimensions, reflecting Jesus’ teaching of the presence and future coming of the kingdom of God (see Kingdom of God)."
Kynes, W. L. (1992). New Birth. In J. B. Green & S. McKnight (Eds.), Dictionary of Jesus and the Gospels (J. B. Green & S. McKnight, Ed.) (574). Downers Grove, IL: InterVarsity Press.
So while atheists can choose to utter ethical statements or incorporate morality into their lives (to whatever extent they are able to do so on their own without the aid of God); they still fall short of what they would be able to accomplish in this respect with God's spiritual rebirth and personal aid not to mention they forgo God's eternal reward as freewill agents who have rejected God, God's kingdom, God's normative morality, God's plan to redeem and transform creation (including people) back to a normatively moral state (something that is impossible for them to accomplish on their own), etc...
As J. P. Moreland pointed out:
"The ontological nature of the image of God, among other things, implies that the makeup of human beings should provide a set of recalcitrant facts for other worldviews. The reasoning behind this claim goes like this:
(1) If Christianity is true, then certain features should characterize human beings.
(2) Those features do, in fact, characterize human beings.
(3) Thus, these features provide a degree of confirmation for Christianity. These features characterize God and, moreover, come from him. He made us to have them.
From a Christian view, God the fundamental being possesses intrinsic value, and his loving, just character is the source of objective moral obligation for human persons. Moreover, since all human beings share the image of God equally, they all have high, equal value and rights simply as such. Thus, a Christian worldview has a natural place for and provides an explanation of:
(1) the existence of intrinsic value,
(2) the reality of objective moral obligation,
(3) high, equal value and rights for all humans.
But these three cannot be accounted for adequately by scientific naturalism.
Evolutionary naturalist Michael Ruse stated:
"Morality is a biological adaptation no less than are hands and feet and teeth. Considered as a rationally justifiable set of claims about an objective something, ethics is illusory. I appreciate that when somebody says 'Love thy neighbor as thyself,' they think they are referring above and beyond themselves. Nevertheless, such reference is truly without foundation. Morality is just an aid to survival and reproduction... and any deeper meaning is illusory."
Given scientific naturalism, it is hard to see how there could be intrinsic value and an objective moral order or why that order would have anything to do with human persons. Moreover, the combinatorial processes of the Grand Story cannot account for the appearance of simple, intrinsic value; thus its existence counts against naturalism and for Christian theism. As atheist Mackie acknowledged: "Moral properties constitute so odd a cluster of properties and relations that they are most unlikely to have arisen in the ordinary course of events without an all-powerful god to create them."\
The recalcitrant nature of human persons for scientific naturalism has been widely noticed even amongst atheists. Naturalists can't appeal to emergence to solve their problems because (1) this is just a label for the problem to be solved and not a real solution and (2) it begs the question against Christian theism in a most egregious way."
When a person is functioning properly-and not censoring, repressing or ignoring their conscience-they have a basic conception of right from wrong/good from evil and they can thank God for that as it is a residual benefit remaining of the Imago Dei, but believing that something is right or wrong and justifying one's belief that something is right or wrong are two very different matters.
In order to have a consistent and reasonable objective moral stance, a moral view in which you can substantiate a claim that this is right and that is wrong in an ultimately meaningful way, you need to have an objective moral basis. Normative morality didn't spew out of the Big Bang.
In atheism, at most, the illusion of moral values was eventually spawned though nothing in biological evolution, especially the alleged selfish-gene phenomenon, is capable of providing the foundation necessary to ground unconditionally binding moral values.
Atheists can pontificate on their morality all they like but they cannot provide a reasonable justification for the existence of nonsubjective universally binding moral values which are ultimately meaningful. For
that, they need God.
Read:
https://www.christiancourier.com/articles/1412-atheism-the-church-of-amorality