There is really no acceptable way of talking to creationists, is there? You can't agree with them, because you actually think they're wrong and need to be honest about it; if you disagree with them but stop talking after a while because you're tired of the whole discussion going nowhere, they think they win because you've stopped talking; and if you disagree with them and keep disagreeing with them, they think they're winning because otherwise why would you be trying so hard to prove them wrong!
Reading through Genesis 1, I find obvious clues that the days being spoken of are not ordinary days:
1. The first three days are said to happen before the creation of the sun and moon. But how can there be evening and morning - sunrise and sunset - without a sun?
2. The flow of the passage is as follows: God creates X, and there was evening, and there was morning, the Nth day. Now nowhere else in the Bible do the words "evening ... morning", in that order, ever signify a full day. They signify the
night portion of a day. See the evidence I accumulated in #150, most notably this verse:
​​​​​​​​Evening and morning and at noon I utter my complaint and moan, and he hears my voice. (Ps 55:17, ESV)
When you realize that "evening and morning" refer to the night, then the bolded phrase makes perfect sense: the psalmist cries out both night ("evening and morning") and day ("at noon"). But if "evening and morning" refer to a whole day then surely "at noon" is superfluous.
3. Taken together, then, the picture is of God working throughout the day and resting at night. Now this is quite unlike what we see in the rest of the Bible. God performs lots of miracles during
our physical nights, like manifesting over the Israelites in a cloud of fire, or putting the Midianites to flight before Gideon's army, or breaking Peter and Paul out of prison on separate occasions. Furthermore, we have categorical declarations from God that He does not sleep at night, again found in #150.
4. So if God does not stop working just for
our nights, then the nights in Genesis 1 must be something different altogether. Not only that, the seventh day appears to be something completely different even from the first six. It has no ending, no "evening and morning" after it; it isn't even announced in the usual way. It is a day of complete rest for God. And it is completely different from the days we experience.
5. As proof of that, the book of Hebrews uses the seventh day to describe God's rest, which some will enter and some will not enter. Now if the seventh day was an actual period of 24 hours a long time ago, then nobody can either enter it or not enter it. It stands to reason therefore that if the seventh day represents any period of human time at all, it must represent a period of human time during which both the Israelites and the readers of Hebrews (which includes us) were alive. Therefore, the seventh day, if it is of any temporal duration at all, is at least two thousand years long. As an additional example, that very passage goes on to say:
Since therefore it remains for some to enter it, and those who formerly received the good news failed to enter because of disobedience, again he appoints a certain day, “Today,” saying through David so long afterward, in the words already quoted, “Today, if you hear his voice, do not harden your hearts.” (Heb 4:6-7, ESV)
It is not as if, when the passages describes "a certain day", God decided on a particular period of 24 hours so that anybody who heard Him within those 24 hours would follow Him and nobody else could! This evidence that "day" can represent a temporally indefinite, but spiritually significant, period of time, comes smack after a mention of the seventh day, which makes it highly significant for our interpretation of Genesis.
6. If the seventh day cannot be 24 hours long (because it is at least two thousand years long), and the first three days need not be 24 hours long (because without the sun, there isn't any intrinsic definition of a day as being 24 hours long), then neither do the middle three days. And indeed, no teaching of Scripture rests on the six days being exactly 144 hours long. You may point to Exodus 20, but: firstly, if the pattern were to be followed exactly, then every person would work exactly 144 hours, and then never work the rest of his life.
Secondly, the pattern is also used to prescribe cycles of seven
years (and the seventh year is explicitly called a Sabbath; see Lev 25:1-4). If the analogy in Exodus 20 has force precisely
because six days in Exodus 20 are 144 hours long, just like six days in Genesis 1, then the analogy in Leviticus 25
cannot have force, precisely because the six years in Leviticus are
not 144 hours long, and therefore cannot be just like six days in Genesis 1. If on the other hand you think that six periods of work and one period of rest is the general pattern being prescribed, regardless of how long each period is - then you are saying that the exact length of the periods in Genesis 1 have no effect on the force of the comparisons in both Exodus 20 and Leviticus 25.
7. The entirely biblical conclusion is one I shall give in the words of theologian C. John Collins:
... the days are God's workdays, their length is neither specified nor important, and not everything in the account needs to be taken as historically sequential.