The Bible does NOT teach universalism. Universalism contradicts the clear teachings of Scripture.
Does eternal just gets to mean eternal when you want it to? Matthew 25:41-46 would be problematic since the same Greek word is used for eternal. Would the righteous only enter eternal life for a certain period of time?
First off, however wrong I believe you to be, I appreciate your dedication to what you believe to be the truth. I also appreciate you asking the question that you did. There is certainly some ambiguity in the word translated as eternal in that passage. (Aionion). For a more in depth look at the word, please see our article posted here.
However, if you aren't interested in reading that article, I will give you a short answer below on possible understandings of the word and what appears to be your greater issue; why Universalists interpret scripture in the way that they do. What is our hermeneutic?
If I said that a man goes into a tall building to talk to a tall man; would you assume that the man is as tall as the building?
Of course not! Adjectives can vary wildly depending on the noun they qualify. Therefore life with God can be qualified differently than punishment from God.
That’s one way of looking at it.
Another way of looking at it is that eternal was used in that time period in the same way that we use celestial in today’s time.
So in the verses that you listed above in Matthew 25:41-46 the life is celestial (Meaning it’s with God): And likewise the punishment is celestial. (Meaning it’s from God.)
There’s nothing in the text that requires anyone to say that we’re speaking of eternal in duration and not simply eternal in nature. The life with God would never end because it’s life with God. The punishment could end, because punishment is properly for the sake of correction.
My own personal view however is a bit different.
Seeing as Matt 25:41-46 is a parable I read it as such. I see myself as both sheep and goat. I do not always care for or visit the sick as I should. I do not always offer food or aid to the poor. Some days I’m a sheep; some days I’m a goat. When I see that passage I see that I have to let go of, and eternally damn the goat. Only the sheep can have life. Only the sheep can truly be said to be in Christ because he has the ‘will’ and ‘mind’ of Christ. I have to become a sheep to truly have life. I believe that the Judgment is the separation of the goat and the sheep.
Some men, repent here and now and daily die to themselves as Paul said of himself. That would be those in Christ. Some men—refuse. They will face judgment. But that judgment is still meant to restore. It’s meant to separate the sheep from the goat. The goat has to die for the sheep to truly live. And I think judgment tends to this result.
I see the verses that speak to a restoration of all things; I see the scripture that speaks to God bringing all things to heel—all things into submission with Himself—the all that died in Adam being the same all restored in Christ. I see Christ as coming to save the lost and I see God accomplishing all of His good pleasure. I believe that even the chastisement of hell—if need be—will serve the purpose of bringing even the most depraved sinner to the foot of the cross and to repentance.
I’m told that God's word will not return to Him void, and I believe that He will not suffer his image to be defaced ad infinitum. Any victory spoken of by a sovereign God must include, not a final separation of those He cannot woo, but must include a superimposing victory that encompasses all that is in subjection under his feet; and I’m told in 1 Corinthians 15 that all things will be subjected to Christ—at which point Christ will submit all things back to the Father that He may be All in All.
This is my hermeneutic. Christ Victorious. Not over some—but over all. I don’t believe it befitting of God to settle for less; and I believe it unbecoming of a son to attribute anything other than ‘all’ to His subjection. God's image in man will not finally be able to resist the love of the Victor. No bastion in hell or sinners heart will eternally prevail against the all consuming—ever pursuant—inexhaustible love of God.