If you're a christian then creation/young earth is very important to protect, without it you have no "fall of man" and therefore no reason for a saviour. Accept

If you're a christian then creation/young earth is very important to protect, without it you have no "fall of man" and therefore no reason for a saviour. Accepting death before sin also complicates matters significantly (as you must if you accept evolution). That and Jesus' legitimacy as a saviour is based off a bunch of prophecy and lineage from some of the earlier texts, including Genesis.