It didn't used to be.

In the first 4 centuries of Christianity, there were six known theological schools that taught three views of Hell.

• Alexandria, Antioch, Caesarea, and Edessa taught Universal Reconciliation

Ambrose (340-397) hugely influenced Augustine.

Ambrose held to Origen's views on apakatastasis.

Augustine (354-430). One of the most important theologians in history.

Most known for his fight against "Pelagianism," which Augustine mistakenly thought Origen was the cause of.

Augustine didn't know Greek, or at least vey little. He therefore misunderstands that the one Latin word aeternus translated both Greek words aidios and aiwnios.

The Orthodox Faith - Volume IV - Spirituality - The Kingdom of Heaven - Heaven and Hell

6 For after all it is only right for God to repay with affliction those who afflict you, 7 and to give relief to you who are afflicted, along with us, when the Lord Jesus will be revealed from heaven with His mighty angels 8 in flaming fire, dealing out retribution ("exacting justice") to those who do not know God, and to those who do not obey the gospel of our Lord Jesus. 9 These people will pay the penalty of eternal destruction ("ruin in the Age"), away from the presence of the Lord and from the glory of His power, 10 when He comes to be glorified among His saints on that day, and to be marveled at among all who have believed—because our testimony to you was believed.

Authorship of 2 Thessalonians is debated

Assuming it is Paul, it must still be put in the context of the rest of Paul's words ("every knee bow, every tongue confess"; "all will be made alive in Christ.")

Eternal = aionios, so "otherworldly destruction" or "destruction of the age."

Destruction ≠ Annihilation. Cf. 1 Corinthians 5:5. Destruction in the LXX is often prelude to restoration. "You will be utterly destroyed...and then I will restore you!"

David Bentley Hart's translation, "They will pay the just reparation of ruin in the Age."

Question about the Millennium: people will still reject Jesus even after 1,000 years of his reign. How likely is it that everyone would eventually turn to Jesus and stay there?

1. Various views on Millennium and Revelation in general. One view is "amillennium," which is the idea that the millennium is happening right now, i.e. "The Church Age."

1. Satan is already defeated and bound. (John 12:31, 16:11)

The critical consensus is that the New Testament contains, for the most part, two kinds of language about the last judgment:

1) One that seems to portend the final destruction of the wicked at the threshold of the restored creation in the Age to Come and

2) Another that seems clearly to promise universal salvation. The question...is which of these two kinds of language can better explain the other?

The former, after all, if the destruction of the reprobate is understood simply as total annihilation, would seem to reduce the latter to vacuous hyperbole.

The latter, however, can conceivably explain the former in terms of a harsh purification that destroys the sinful self, but only for the sake of the resurrection of the redeemed creature. (DBH)

The belief that a God of infinite intellect, justice, love, and power would condemn rational beings to a state of endless suffering, or would allow them to condemn themselves on account of their own delusion, pain, and anger, is probably worse than merely scandalous. It may be the single most horrid notion the religious imagination has ever entertained, and the most irrational and spiritually corrosive picture of existence possible.

— DBH

“Love your enemies…be perfect as your father is perfect.”

The irresoluble contradiction at the very core of the now dominant understanding of Christian confession is that the faith commands us to love God with all our heart, soul, and mind and our neighbours as ourselves, while also enjoining us to believe in the reality of an eternal hell; we cannot possibly do both of these things at once.

— DBH

If the hypothesis were offered us of a world in which ... millions [should be] kept permanently happy on the one simple condition that a certain lost soul on the far-off edge of things should lead a life of lonely torture, what except a sceptical and independent sort of emotion can it be which would make us immediately feel, even though an impulse arose within us to clutch at the happiness so offered, how hideous a thing would be its enjoyment when deliberately accepted as the fruit of such a bargain?” — William James

The obscenity of belief in an eternal hell - ABC Religion & Ethics