"The $50,000 offer is to wake people up out of a stupor," Marcussen tells WorldNetDaily. "People wake up when there's money involved."

Marcussen, who says he has the money ready to pay if someone is successful, is making the offer to encourage people to read the Bible for themselves, instead of accepting without question what religious leaders have been instructing.

"Millions of people believe and have confidence in their clergy that what they're being taught is true," says Marcussen. "They'll find out that the clergy is not teaching from the Bible."

Marcussen, 52, is not only a preacher in his local church, he's also a physical therapist, nutritionist, marriage counselor and author of six books. One of those works, "National Sunday Law," focuses on the Saturday-vs.-Sunday debate. Marcussen is asking people to read that book before applying for the reward. (It can be read for free online.)

As a college student in the 1970s, Marcussen made a similar, albeit smaller, challenge. He posted an ad in a local newspaper starting with a $500 reward and ending up at $1,000. "Certain preachers really got excited," he says. "But the only thing they couldn't do was produce a Bible verse [as proof]."

Experts on biblical scripture tell WorldNetDaily that Marcussen has little need to worry about paying out the money.

"I am afraid that you are not going to find an exact Bible verse to counter the good pastor's challenge and collect," says James Efird, professor of biblical interpretation at Duke University Divinity School in North Carolina. "As far as I know, there is no verse which specifies that Sunday is the day for Christians to observe the Sabbath."

Indeed, neither the words Saturday nor Sunday appear anywhere in most translations of the Bible. Days of the week are referred to by number, starting in the first chapter of Genesis in the account of creation. It was after the work of creating that God made special note of one day of the week: "And God blessed the seventh day, and sanctified it: because that in it he had rested from all his work which God created and made" (Genesis 2:3).

In the Ten Commandments, the seventh day was made the focus of the fourth mandate: "Remember the sabbath day, to keep it holy ... thou shalt not do any work ... 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" (Exodus 20:8-11).

The word sabbath comes from the Hebrew root word "shabbat," meaning to rest, cease or desist. Scholars say the word in Bible scripture not only refers to the weekly day of rest, but also the annual festivals of God such as Passover and Day of Atonement. It additionally refers to a sabbatical year, and it's the term denoting one week. The phrase "first day of the week" occurs eight times in the King James translation of the New Testament, mostly dealing with the circumstances of Jesus' resurrection.

In the lexicon of modern society, the debate over which day is holy – that is, set apart to God – goes unresolved by the editors of Webster's New World College Dictionary. While the first definition of sabbath calls it "the seventh day of the week (Saturday), set aside for rest and worship and observed as such by Jews (from Friday sunset to Saturday sunset) and some Christian denominations," its second meaning defines it as "Sunday as the usual Christian day of rest and worship."

"There's a fear factor among preachers," says Marcussen, on why churches don't have their members look into this issue. "They're afraid their sheep will start reading the Bible, and they know they'll lose their sheep."

One expert who has spent his career researching and explaining the Sabbath debate is Dr. Samuele Bacchiocchi, a retired theology professor at Andrews University in Michigan. He tells WorldNetDaily two factors are responsible for the shift from one day to another: "Anti-Judaism caused the abandonment of the Sabbath, and pagan sun worship influenced the adoption of Sunday."

Bacchiocchi says the Church of Rome, which grew into the Roman Catholic Church, had great influence in promoting Sunday observance. "The Church of the capital of the empire, whose authority was already felt far and wide in the second century, appears to be the most likely birth-place of Sunday observance," he writes in his book, "From Sabbath to Sunday: A historical investigation of the rise of Sunday observance in early Christianity."

In May 1998, Pope John Paul II issued an apostolic letter on the subject, entitled Dies Domini (The Lord's Day). In it, the pontiff refers to the origins of Sunday-keeping.

"In the weekly reckoning of time, Sunday recalls the day of Christ's Resurrection," writes the pope. "It is Easter which returns week by week, celebrating Christ's victory over sin and death, the fulfillment in him of the first creation and the dawn of 'the new creation.'"

The pontiff goes on to state that though Sunday has become a time for cultural, political and sporting events, it has a significance that shouldn't be ignored. "Unfortunately, when Sunday loses its fundamental meaning and becomes merely part of a 'weekend,' it can happen that people stay locked within a horizon so limited that they can no longer see 'the heavens.'"

Though Protestant churches have some significant differences with Catholicism, one thing often agreed on today is Sunday observance.

"The church always met on Sunday throughout the New Testament," says Rev. Jerry Falwell, chancellor of Liberty University in Virginia. "Saturday is clearly the Sabbath as is recorded many times in the Old Testament. In Christian Church tradition, Sunday became 'the Lord's Day' when Jesus rose from the grave."

The actual times of Jesus' crucifixion and resurrection are not universally agreed on either. "I personally believe he was crucified on Wednesday evening ... and rose after 6 p.m. Saturday evening," Falwell tells WorldNetDaily. "Others believe he died on Friday ... But the point is, he did rise on Sunday, which, in Jewish tradition, started the evening before at 6 p.m."

Falwell is among those who believe which day is chosen is not of great significance. "I don't think Saturday or Sunday are more sacred than other days," he says. He also points out there have been so many calendar changes over the years, chronologists are not even certain that a day of the week in the 21st century matches the same day from centuries ago.

Most scholars agree that biblical references to "the sabbath day" denote the seventh day of the week. But in the years to come after Jesus rose, the first day of the week came into competition with Saturday, and at times both days were being observed side by side. The ostensible church was divided on the issue, choosing different days to regard as holy.

"It may be that Sunday was originally one of the [pagan] Roman festival days," explains Professor Efird at Duke, "but so were several others that the church adopted in its evolution, [for example:] Christmas."

Marcussen condemns the change in day of observance. "It's the greatest hoax of all time, foisted upon the world for hundreds and hundreds of years," he says. His zeal on the matter reflects his belief that citizens of the United States and other countries will be forced to choose sides on the issue in the so-called "end time" mentioned in Scripture.

"Sunday worship is the mark of the Papacy's authority," Marcussen writes in his book. "Sunday worship is the 'mark of the beast!'" Yet he insists he is not attacking anyone's faith, but rather trying to lead people to the Bible, Jesus, and eventually Heaven.

"I love all these ministers who teach falsehoods," Marcussen says. "Many are honest – they're not all crooks – they believe Sunday is God's day ... this offer will help them find the truth."

Marcussen expects his challenge to be eye-opening for many who never thought about the issue, and he thinks it will spark serious global attention. "The impact of this is going to be like an atomic bomb, it will mushroom all over the world."