You may have experienced are seen the accusation: Young-earth belief is the same as flat-earth belief. If you believe one, you must also believe the other because both are silly. They are both equally science-deniers and misusing Scripture.
The allegation is an attempt to link the science-deniers of flat-earth community with young-earth creationists. Instead of addressing the evidence or claims of the creationist argument, it is nothing more than another ad hominem attempt to paint creationist as unthinking, anti-science, or just stupid.
I know very few individuals that believe in the flat-earth. Of those few individuals, while they do actively deny science, they generally are intelligent and thoughtful. And here is the first distinction between young-earth creationism and flat-earth adherents. Young-earth does not deny science. Contrary to the false accusation. Young-earth is very scientific. Perhaps more than evolutionary or old-earth creation worldviews.
Young-earth acknowledges the importance of worldview and its affect on the process of science. Old-earth and evolution (OE/E) however, almost always does not. OE/E is unaware of the impact of a worldview that demands deep-age on the way their initial observations, or the formation of their hypothesis, or the impact on the design of any experiment to test their already biased hypothesis. They deny there is any impact of worldview on their observations and analysis of the data and most certainly does not affect their conclusions. Their inability to perceive the affect of their worldview adds another layer of obfuscation of the truth.
Biblical and Theological Consequences
There are negative biblical, theological, cultural, social, and personal consequences to holding an old-earth or evolutionary worldview. There are none to confessing the world is spherical Actually, there is a benefit to understanding and confessing that God created a spherical world in a three-dimensional universe.
The god of flat-earth worldism is smaller than the God of an expansive three-dimensional universe. This is both simply but more than the cause/effect analogy. The more expansive effect requires the greater cause. From a first approximation approach, this alone is sufficient benefit of spherical over flat.
As with any man-made idea, the god of flat-earth worldism can easily become the person holding the flat-earth view when their reason for holding that view is a sense of greater spirituality or spiritual knowledge than the poor, deceived nonflat. It has become Gnostic taking on a self-worship component. This can also be said of young-earth and old-earth worldviews. Therefore, we must all be on guard to prevent it from characterizing our thinking.
Although it can be a temptation of all three views, the young-earth is more outward-emphasizing. Confessing that scriptural revelation is superior to natural revelation and hence to scientific truth claims is a hallmark of young-earth. That worldview component can provide a protection against self-importance and self-elevation.
Flat-earth makes no claim on why God created the world flat. Young-earth claims God had extreme purpose in the act of, method of, timing of creation. God, in revealing Himself and what He intends for His creation, did so by creating the world in six literal days. That purpose is woven into the creation narrative, and is lost in an OE/E view.
The moral, cultural, and social impact of flat-earth vs young-earth are vastly different. Families composed of a father and mother with the purpose of raising godly children is established in a young-earth worldview. OE/E corrupts the authoritative value of male and female, family, marriage. The origin and meaning of sin and redemption is also preserved and emphasized by young-earth but removed when the real historical events in which these are revealed are denied by OE/E. Flat-earth view provides no benefit regarding these essential truths.
Young-earth creationism provides theological, and therefore moral, benefits that are not associated with flat-earthism.
The Spherical Earth is Understandable Apart from Worldview
Anyone with basic observational skills and basic math skills can demonstrate the earth is spherical and calculate the radius or circumference of the earth.
The earliest known calculation of the circumference of the earth was by Eratosthenes of Cyrene (276 – 194 BC). Since he was motivated to make the calculation, it must have been known or strongly suspected by the intellectuals of his day that the earth was spherical. It is rational to assume this understanding could have been present much earlier than Eratosthenes.
Understanding how Eratosthenes measured the circumference clearly shows that he already knew the earth was spherical. Something previous in his experience and education established that the world was spherical. Eratosthenes used simple mathematical tools and common everyday experience of the shadows to calculate the circumference.
Eratosthenes recognized the Sun had to be distant. Meaning very far away. Further than just an arch or projection above a flat earth. That Sun then would provide light unaffected by “closeness”, and the light would be unchanged source directionality at two distant places on the surface of the Earth. Therefore, the difference in the angle of the light at two distant location on the Earth on the same day was both confirmation the earth surface was curved, and could be used to calculate the radius of curvature.
This knowledge that Eratosthenes acquired (the circumference of the Earth) was readily available to any person standing on the surface of the Earth in his day and in ours.
The age of the earth is fully dependent on worldview. OE/E looks for and finds scientific data that supports an already accepted deep-time requirement. Young-earth looks for and finds scientific data that supports young-earth. However, that doesn’t make them equivalent. The young-earth scientist finds their data in repeatable, experimental evidence (C-14 in diamonds, coal, fossils; soft-tissue in fossils; helium diffusion rates from zirconium crystals). But, that evidence is not viewed as proof of a young-earth. It simply confirms what scripture teaches.