If you want to believe that "few there are who find" the narrow way to salvation, and also that God is omniscient, then God decided to create a huge number of people that He knew ahead of time would sin and never accept salvation. Why create them in the first place? Why not create only those who you know will sin, but who you also know will avail themselves of the redemption that you plan to offer?
If the reality of "free will" has to be demonstrated by allowing people to persist in sin to the ultimate degree, why not create just one person who you know will suffer that fate, and use that as an example instead of creating billions and billions of people who will take the "broad way" to "destruction"?
If either endless punishment or annihilation is true, then in the former case (eternal punishment), God could have had the writers of scripture use words available to them in both Greek and Hebrew to describe both concepts without any possibility of a doubt, instead of using words like "aion" and "olam" which are not very specific. You would also think that maybe God would have warned Adam and Eve about these terrible possibilities (ECT or annihilation) instead of just saying "dying you will die" and not elaborating any further about what "dying" entails. In order for God's statement about "dying" to be a deterrent to disobedience, there would have to be some kind of understanding about what "death" is. Which brings up my problem with the annihilation view. The bible uses words dealing with "death" in so many ways, it isn't clear how the term is being used in each of the contexts in which it is found. It is left quite open to various interpretations. Which is why many of the the early church fathers had widely varying views on the scope of God's salvation of man. If universal salvation is so clearly heretical as many people claim, why was Gregory of Nyssa allowed to play such a prominent role in developing the concept of the trinity at the council where the Nicene Creed was drafted? Was, and is, this council and the formulation of this creed, such a trivial matter that the church could afford to let an open teacher of universalism even as much as attend the council, much less play an important role in it's work?
Why is there so much (apparent, but not real) equivocating in what God says? One minute He is saying to Israel "your wound is incurable" and then later on He says He is going to cure them? In Jude He says that Sodom and the surrounding area are suffering the vengeance of "eternal fire", but in Ezekiel 16 He says that Sodom will have it's captives restored and will be given to Jerusalem as a daughter. There are many other examples. The following are from a book titled "Hope Beyond Hell" which can be found at tentmaker.org -
A Moabite is forbidden to enter the Lord’s congregation forever [olam]. But only until the 10th generation. (De. 23:3).
Hills are everlasting [olam]. But only until made low and the earth is burned up (Ge. 49:26; De. 33:15; Is. 40:4; 2Pe. 3:10).
Mountains are everlasting [olam]. But only until they are scattered (Hab. 3:6).
A slave serves his master forever [olam]. But only until death ends his servitude (Ex. 21:6).
The Mosaic covenant is everlasting [olam]. But only until it vanishes away (Le. 24:8; He. 8:7-13).
The Aaronic priesthood is everlasting [olam]. But only until the likeness of Melchizedek arises (Ex. 40:15; Nu. 25:13; He. 7:14-22).
These “stones” are to be a memorial forever [olam]. Where are they now (Jos. 4:7)?
Even passages that do not use the word olam, but signify unchanging, are not so when God is involved. Nothing can deter Him from achieving His purposes. For example:
Israel’s affliction is incurable. But only until the Lord restores health and heals her wounds (Jer. 30:12, 17).
Samaria’s wounds are incurable. But only until the Lord brings them back and restores them (Mic. 1:9; Ez. 16:53).
Egypt and Elam will rise no more. But only until the Lord brings back their captives (Jer. 25:27; 49:39; Ez. 29:14).
Moab is destroyed. But only until the Lord brings back the captives of Moab (Jer. 48:4, 42, 47).
Augustine raised the argument that since aionios in Mt. 25:46 referred to both life and punishment, it had to carry the same duration in both cases.5 However, he failed to consider that the duration of aionios is determined by the subject to which it refers. For example, when aionios referred to the duration of Jonah’s entrapment in the fish, it was limited to three days. To a slave, aionios referred to his life span. To the Aaronic priesthood, it referred to the generation preceding the Melchizedek priesthood. To Solomon’s temple, it referred to 400 years. To God it encompasses and transcends time altogether.
Thus, the word cannot have a set value. It is a relative term and its duration depends upon that with which it is associated. It is similar to what “tall” is to height. The size of a tall building can be 300 feet, a tall man six feet, and a tall dog three feet. Black Beauty was a great horse, Abraham Lincoln a great man, and Yahweh the GREAT God. Though God is called “great,” the word “great” is neither eternal nor divine. The horse is still a horse. An adjective relates to the noun it modifies. In relation to God, “great” becomes GREAT only because of who and what God is. This silences the contention that aion must always mean forever because it modifies God. God is described as the God of Israel and the God of Abraham. This does not mean He is not the God of Gentiles, or the God of you and me. Though He is called the God of the “ages,” He nonetheless remains the God who transcends the ages.
In addition, Augustine’s reasoning does not hold up in light of Ro. 16:25, 26 and Hab. 3:6. Here, in both cases, the same word is used twice—with God and with something temporal. “In accord with the revelation of a secret hushed in times eonian, yet manifested now…according to the injunction of the eonian God” (Ro. 16:25, 26 CLT). An eonian secret revealed at some point cannot be eternal even though it is revealed by the eonian God. Eonian does not make God eternal, but God makes eonian eternal. “And the everlasting mountains were scattered.…His ways are everlasting” (Hab. 3:6). Mountains are not eternal, though they will last a very long time. God’s ways however, are eternal, because He is eternal.
One other note for those who insist on the necessity of aionian meaning eternal for both "life" and "punishment" in Matt. 25:46 - When the age (aion) that the phrase "aionian life" refers to comes to an end, death will have already been destroyed, swallowed up by life. Life will be all that is left, so death is limited to the "aions", life is not.