I agree with [old earth creationists] that people can believe the Gospel without reference to Genesis. The problem is that the Bible doesn’t present our sin problem as a mere existential crisis untethered to the history of humanity and the world (The good news without the bad news is no news at all!). History grounds theology; that’s not true just in the New Testament, but also in the Old, from which the New Testament got its concern for history (Redemptive history and evolution don’t mix and Remembering God’s mighty acts: The Bible calls us to read its narrative in ways that contradict ‘deep time’). The issue isn’t that Genesis is a part of the gospel; the issue is that playing fast and loose with the history of Genesis can lead people to distort or disregard the gospel. Why? The Gospel is not so easily removed from its redemptive-historical context as long-agers would like (for a book-length treatment of this, see Creation, Fall, Restoration).
— Shaun Doyle (Creation Ministries International)