I believe the Christian astronomer Hugh Ross uses the Day Age theory to reconcile his scientific understanding of the universe with Scripture.
Are you implying a similar model.
P.S. I am not claiming Christians that try to take a non-straightforward reading of the text from Genesis 1-3 and Exodus 20:8-11 cannot be believers. I just believe they have a tendency to instill confusion into those who they witness to, because of the evident difference between what they say and what the passages in the Bible say.
Exo 20:8-11
8 Remember the sabbath day, to keep it holy.
9 Six days shalt thou labour, and do all thy work:
10 But the seventh day is the sabbath of the LORD thy God: in it thou shalt not do any work, thou, nor thy son, nor thy daughter, thy manservant, nor thy maidservant, nor thy cattle, nor thy stranger that is within thy gates:
11 For in six days the LORD made heaven and earth, the sea, and all that in them is, and rested the seventh day: wherefore the LORD blessed the sabbath day, and hallowed it.
A direct comparison. I believe the Holy Spirit is competent enough in His communication to make sure if there were a difference to point it out here.
Isn't that precisely what God does in Genesis with His specific mention of evening and morning for each day?