During a discussion about evolution in regards to its relationship with God, it is not entirely uncommon for proponents of evolution (who are typically also atheists, or at least nonbelievers) to proclaim that evolution isn't a theory about abiogenesis (the origin of life), and that to argue about abiogenesis is not relevant to a discussion about evolution. However, those same proponents of evolution nearly always use it as an opposing theory against creationism, which directly addresses abiogenesis.
The problem with such a claim is that in making the case clearly that evolution does in fact not answer the question of where life started, the participant in this debate has actually indirectly agreed that evolution in no uncertain terms is not a substitute for God and thus does not refute creationism. This certainly is not truly a problem if you genuinely do only intend to argue about whether evolution as a theory of diversification of species is valid, but more often than not, these same people are on the side of arguing against God.
In case the connection is not immediately obvious, to clarify, if evolution cannot explain why life started to exist in the first place, then God has not been ruled out as a possible reality even if evolution is true. The problem I'm pointing out is that somehow, evolution proponents have taken to claiming that evolution is not about abiogenesis, while simultaneously claiming that evolution disproves creationism, a theory that deals directly with abiogenesis. I have never seen this claim made by someone who is simply passing through to ensure people know what the theory actually entails - it is always someone arguing explicitly against God's existence as a possible reality. Perhaps, if I give a generous benefit of the doubt, these are the the same atheists doing this, but so far the evidence is sparse.
The irony is the exact point that they are so quick and adamant to clarify - that evolution and the common ancestor are totally different theories that don't depend on one another - nullifies any point they are attempting to make about evolution vs. God. Their own declaration that evolution does not address the question of where life originated immediately destroys any argument that can be made regarding whether or not evolution can replace God.
To boil it down further, if evolution does not and is not intended to answer the question of where life came from, then it actually has no bearing on whether or not God exists. Evolution could be true and God can exist at the same exact time with absolutely no contradiction or inconsistency.
Evolution can only challenge God's existence if it can explain how life came to be. If it does not, and if by the atheist's own admission it is not intended to, then both can be true simultaneously with no conflict. The "evolution vs. creationism" argument is apparently not solved, but rather entirely voided. If evolution is not concerned with abiogenesis, then it's not a valid against against the existence of God.
The confusion from the atheist likely comes from assuming that God as described in the bible (creating humans from dust, etc.) must be what exists in order for God to exist. The reality is that God as a timeless, spaceless, immaterial, all powerful, and personal Creator does not depend on the bible's explanation of Him to exist. Surely, if evolution as the origin of humanity were true, it would call into question the validity of the bible, but it would not call into question the existence of a Creator.
I won't go any further into this as my intention was just to point out this inconsistency in ideological debate. I don't have the energy to delve any deeper at the moment.