1) There are many instances in Bible prophecy where a day means a day and a year means a year. The Bible prophesied that Abraham’s children would be afflicted for 400 years (Gen 15:13) and that the Jews would be in captivity for 70 years (Daniel 9:1-2). Jonah prophesied Nineveh would be destroyed in 40 days (Jonah 3:4), which did not equate to 40 years. In Genesis 6:3 God prophesied there would be a period of 120 years before the flood, which did not equate to 43,200 years. Here, days are days and years are years. Then to apply a year-day principle is arbitrary.

2) Adventist and others primarily build the case for the year-day principle from Numbers 14:34 and Ezekiel 4:4. However, no year day prophetic principle is established in Numbers 14:34: 

“In accordance with the number of days that you spied out the land, forty days, for every day you shall suffer the punishment for your guilt a year, that is, forty years, and you will know My opposition“. 

Numbers 14:34 deals with a divine sentence: just as you explored the land for 40 days and were unfaithful to me, now you will roam the desert for 40 years. There is no prophecy in this passage, or symbolic vision, or symbolic time period. Both data are literal spans of time.

3) The same is true in Ezekiel 4:4-5:

“For I have assigned you a number of days corresponding to the years of their wrongdoing, 390 days; so you shall bear the wrongdoing of the house of Israel. After you have finished this, lie down again, this time on your right side, and bear the sin of the people of Judah. I have assigned you 40 days, a day for each year”. 

Again, there is no symbolic vision involved here, no symbolic time period, no prophecy. The relationship between the 390 days of witnessing by Ezekiel and the 390 years of Israel’s sin is typological/literal, not symbolic. One literal period stands as the literal type of the other: a period of sin by Israel is a type of God’s forbearance. The prophet’s lying down for 40 days is a type of Judah’s 40 years of transgression.

Don Neufeld, a theologian, and an associate editor for the Seventh-day Adventist Bible Commentary wrote in Adventist Review:

“Some have felt that Num. 14:34 and Eze. 4:6 establish the year-day principle as needing to be applied to all time prophecies. But a careful examination of these passages shows that the principle is applied only to specific cases and that there is no general statement in these passages suggesting that a universal principle is set forth. In fact, Seventh-day Adventists do not apply the principle consistently to all time prophecies. For example, the length of the millennium is stated in Revelation 20:3, 5, 7 as being ―a thousand years. This is accepted literally. If the year-day principle were applied, the length would be 360, 000 years. (Source: This Generation Shall Not Pass, in Adventist Review, April 5, Washington D.C,: Review and Herald Publication Association, also quoted in Desmond Ford, Daniel 8:14: the Day of Atonement and the Investigative Judgment, Cassellbury, FL.: Euangelion Press, 1980, pp.85-87.)

Seventh-day Adventists do not apply the principle consistently! 

4) The “seventy weeks” of Daniel 9 cannot prove the year-day principle either, because the expression is actually “seventy ‘sevens“‘ (Dan. 9:24). We know that Daniel 9 is talking about “weeks of years,” not “weeks of days,” but this knowledge comes from the context.

5) The formula “a day for a year” was not used by the New Testament, nor by the early Christians. It was first suggested by a medieval Jewish scholar, and only later adopted by some Christian expositors. It reached its zenith of acceptability in the eighteenth and nineteenth centuries.

6) There is no way any sensible Christian who desire to handle Scriptures carefully could apply a day-year principle to Daniel 8:14, because in Daniel 8:14, the Hebrew for evening and mornings is ‘ereb-boqer’. It is not the usual Hebrew word, yom for day. So, where exactly is the biblical key that, in prophecy, “one evening plus one morning” equals one year rule? Don’t we, as creationists, insist that the presence of the words “evening and morning” in Genesis 1 implies 24-hour days? Who gave SDAs the right to use evening to morning = 1 year rule when God has not even specified such a rule? If God wanted to say 2300 years, he would have said it so like He does elsewhere in Bible prophecy. 

See also:

1) Our verse-by-verse complete Daniel Commentary

2) Our verse-by-verse complete Revelation Commentary