Ok I'll get started soon with why I believe the Bible. But before I do, I'd like to mention that I do not think that the first days of creation were 24 hours each. Some do, I don't.
Genesis 1 don’t mention hours at all, but it does each day comprise of an evening and a morning, and does so in 6 times (Genesis 1:5, 8, 13, 19, 23 & 31)...
“Genesis 1:5” said:
And there was evening and there was morning...
...followed by specific day (eg 1st day, 2nd day, 3rd day, etc), first instance...
No one is suggesting Genesis day being 24-hour day. To suggest or claim that, is simply strawman. But the 6 verses do contextually say each day comprising of both evening and morning.
It doesn’t say in those 6 verses (verses 5, 8, 13, 19, 23 & 31), “1 year”, “100 years”, “1000 years”, “1 million years”, etc. No where in those 6 verses contextually mentioning any year.
The evening-and-morning don’t equal to “a thousand years”, as some Christian creationists like to think, by using the simile in the NT 2 Peter 3:8...
“2 Peter 3:8” said:
8 But do not ignore this one fact, beloved, that with the Lord one day is like a thousand years, and a thousand years are like one day.
The context to verse 5 and the other 5 verses in Genesis 1 is that an evening and a morning make up a day.
The only time, the word “year” being used in Genesis 1, after the creation of the Sun and Moon on the 4th day, where it associate the calendar and seasons with the year:
“Genesis 1:14 said:
...and let them be for signs and for seasons and for days and years...
Creationists cannot use Peter’s day=1000-year, because Genesis 1 never say it. When they do use this illogical simile, they are only demonstrating how dishonest creationists are, by taking the creative days out-of-context.