And God said, “Let there be light”, and there was light. And God saw that the light was good. And God separated the light from the darkness. God called the light Day, and the darkness he called Night. And there was evening and there was morning, the first day.  (Genesis 1:3-5)

Day is יוֹם yom in Hebrew and the word has a range of meanings including a sidereal day to an age; it means a defined period of time.

Time is God’s construct.  Like matter and energy of the material world, time is needed to give direction and causality to those properties, and is therefore part of His creation.

And God said, ‘Let there be lights in the expanse of the heavens to separate the day from the night. And let them be for signs and for seasons, and for days and years,and let them be lights in the expanse of the heavens to give light upon the earth.’ (ibid 1:14-15)

A year is defined by the rotation of earth around the sun, a month by the moon around the earth and a day by the earth spinning once on its axis – it should be noted that a week, a period of seven days is decreed only by God’s word and is not phenomenal (adoption by the world of the seven day week is an unconscious acknowledgement to God.) 

In the Bible periods of time are always expressed accurately, in actuality and not symbolically.  The Israelites wandered the Sinai for forty years; Abijah ruled Judah for three years, while his son, Asa, died in the forty-first year of his reign and his son, Jehoshaphat, was enthroned twenty-five years.  Time spans are even given in months and days, for example Jehoiachin ruled for just three months and ten days in Jerusalem – see 2 Chronicles for these kings’ supremacy.  Thus, time and time-lines are historical.

And when it comes to future events, such as the Millennial Kingdom, there is no reason to doubt that the thousand years duration is other than exactly portrayed in Revelation 20.

So, what of the creation week?  Is a day a twenty-four-hour period (the hour being a human invention)?  Or is it 2 billion years as some interpreters suggest in order to combine worldly thinking understanding with Biblical truth.

The following observations can be made:

• God declares the first day before the sun and moon are created, which happens in the fourth day; therefore, a sidereal day has not been established.

• For God, eternal and so existing out of time, a moment on earth is as nothing. As Peter tells any doubters:

But do not overlook this one fact…that with the Lord one day is as a thousand years, and a thousand years as one day. (2 Peter 3:8).

• There are other places in the Bible that ‘Day’ is used to cover a longer time-span, take the Day of the Lord:

‘Therefore wait for me,’ declares the Lord,
    ‘for the day (yom) when I rise up to seize the prey.
For my decision is to gather nations,
    to assemble kingdoms,
to pour out upon them my indignation,
    all my burning anger;
for in the fire of my jealousy
    all the earth shall be consumed…’  (Zephaniah 3:8)

The programme of events that fall within the Day (Yom) of the Lord begin with the return of Christ in glory, earthly judgment and a purging of heaven through to the establishment of the new creation, broadly covered in Isaiah chapters 61 (where Jesus leaves unspoken 61:2b in the synagogue in Nazareth – Luke 4:18) onwards and is called a year.

Echoing the imagery of Revelation 12:2, but personifying Jerusalem to represent Israel:

Before she was in labour
    she gave birth;
before her pain came upon her
    she delivered a son.
Who has heard such a thing?
    Who has seen such things?
Shall a land be born in one day?
    Shall a nation be brought forth in one moment?  (Isaiah 66:7-8)

To return then to the creation week, there is no reason to believe that duration is represented figuratively; the issue is only that a ‘day’ may defined as God determines.