World-renowned evangelist Billy Graham warns that the "days of Noah are returning to the Earth," and should it finally happen, then it will be a "climactic event that will ring the curtain down on history."

"The Bible many times warns that toward the end of history as we know it, there will be a return to pre-flood conditions of gross sin and wickedness," Graham writes on his Decision Magazine. "The Scripture says concerning the people of Noah's day, 'Then the Lord saw that the wickedness of man was great in the earth, and that every intent of the thoughts of his heart was only evil continually' (Genesis 6:5)."

Graham adds that in the last days, there will be "perilous" things happening, what with men being "lovers of themselves, lovers of money, boasters, proud, blasphemers, disobedient to parents, unthankful, unholy, unloving, unforgiving, slanderers, without self-control, brutal, despisers of good, traitors, headstrong, haughty, lovers of pleasure rather than lovers of God, having a form of godliness but denying its power."

Even though the Bible did not say exactly when that judgment will come, "there are many indications that we are now living in the closing period of history."

People are called to repent and turn to Christ as the day of judgment draws near, says Graham. There are many who mistakenly assume they are already saved, but Graham warns they only have a "false notion" of what it's like to truly be a Christian since they continue living life any way they like.

"In their manner of living, they are indistinguishable from the world," he says. "It is true that they attend church with some regularity and do many good works, but they are not resting in the blood of Jesus Christ for their salvation, and they are not doing the works of faith that are required as an evidence of one's relationship with God."