Quran has informed about the future in a miraculous way after the defeat of the Romans. Usually the defeated nations can not stand up strongly in short period to defeat those who defeated them. Allah said in Sura Rum: And after being defeated they (Romans) will defeat (their opponents) within few years Bidh'i بضع سنين which is between three to nine or ten years. The exact number of years was not mentioned because the victory of the Romans on their enemies took few years through many battles and was not in just one year.
'The battles took few years till the Rum defeated their enemies. Quran said: في بضع سنين Within or during few years, which is exactly what happened.
Allah (SWT) created all His creatures for showering on them His countless bounties and unlimited Mercy. We read in Qur'an: (Except those on whom Your Lord Has bestowed His Mercy, and for that He did create them). (Sura 11, verse 119).
Allah never created people to send them to hellfire, except those insist on criminal acts and continue committing injustice and die on such criminal acts.
Allah, The Most Merciful, The Most Compassionate gives every human being thousands and thousands of chances to believe in thr Truth and do good then enter the Paradise.
Allah (SWT) Has promised every one who believes in Him as The One God to go to Paradise as the Prophet Muhammad (SAWA) said: Paradise is the ultimate place for all believers in Allah الجنة للموحدين.
It is not correct the think majority of people since the time of Adam were atheists or non believers. Majority of human beings are believing in The One God which is part of the instinct knowledge even if the cultures and titles are different.
'The Mercy of Allah is much more greater than what we think and He will deal with His creatures with His great Mercy except the enemies of Allah.