That Adam’s nature changed and become somehow more sin prone is dogma with most Genesis literalists. However this is not a 100% affirmed by all Christadelphians. Creationists (variously YEC/OEC) have come to the same conclusion as most evolutionary creationists that such a change is NOT found in the Bible.The problem many literalists face is they start off with a mis-understanding of very good, believing it refers to some mysterious state despite the biblical use. Having constructed Adam in some unhuman state, they must reconcile him to the reality of our position of being sin prone. A change in nature is their solution. Strangely this change, the most critical consequence of his sin according to these literalists, is not mentioned in Genesis 3.
The problems in this constructed situation have been noted by creationists as well as those who are of an evolutionary creation bent.
Bro Roberts expressed that Adam had our impulses to sin in 1869 saying ““The impulses that lead to sin existed in Adam before disobedience, as much as they did afterwards; else disobedience would not have occurred. These impulses are in their own place legitimate enough” Subsequent to this, one of his last articles provided a contrary position when in 1896 he wrote “That the flesh resulting from the condemnation of human nature of death because of sin, has no good in itself, but requires to be illuminated from the outside”. He appears to be contradicting his position and stating our human nature was a consequence of Adam’s sin. While he provided various references under this statement, they all refer to the current state of man rather than speak to a change.
As elsewhere referenced, Bro Thomas was of the view that our nature was present in Adam and Bro Sargent in 1969 confirmed this interpretation of the Doctor’s words. Sargent was quite specific:
“The quality of being “very good” is therefore not peculiar to the man, nor does it bear some special significance for him; as “a beast of the field” it must include the serpent. Clearly, being “very good” in the sense in which it is here used of the animal creation does not exclude “the thinking of the flesh”. May we not say that the capacity for the desires of the flesh, the eyes and the mind is necessary to man’s probation; without it he could not have been put to the test, or have developed character.
The second point is that while the “very good” animal or natural body was “capable of an existence free from evil as long as its probationary period might continue”, it was also capable of yielding to natural desires; and by his quotation from James Dr. Thomas shows that the exciting of desire “by what from without addresses itself to the five senses” is not peculiar to Adam, it is the way we are all tempted.
Bro Thomas’ understanding was based in part on James 1:14-15 “But every man is tempted, when he is drawn away of his own lust, and enticed. Then when lust hath conceived, it bringeth forth sin: and sin, when it is finished, bringeth forth death.”. (Note the very clear use of death to mean something more than mortality in a context very much about the process of sin applicable to Adam). This is precisely the pattern set out in the Garden, the lusts or impulses in Eve, legitimate of themselves, were excited down a bad path which led to sin and sin led to death. It is common practice in our community to parallel Eve’s observations and error with the lust of the flesh (good for food) lust of the eyes (pleasant to the eyes) and the pride of life (to be desired to make one wise) described in 1 John 2:16.
More recently David Levin simply stated “Adam and Eve clearly have human nature from their creation. There is nothing unique about them.”
Let’s be clear, we think there were massive consequences for Adam and Eve because they sinned. They died as promised. The consequences were far reaching and are described IN DETAIL in Genesis 3. A new proneness to sin (something we all experience now) is not mentioned as a consequence. If it was important you would think the angels would have mentioned it.
 Roberts R “The Relation of Jesus to the Law of sin & death” The Christadelphian, volume 6 page 85 (1869).
 Roberts, R “The Melbourne Synopsis” The Christadelphian, Vol 33 page 340 (1896).
 Sargent “Dr Thomas on Adam’s Temptation” The Christadelphian Volume 106, page 124, (1969)
 Levin, David (2011) The creation text: studies in early Genesis” The Christadelphian Tidings Publishing Company, Livonia Michigan USA page 222