Why does 1 Corinthians 3:11-15 make it sound like the separation of goats and sheep on the day of judgment are people who are saved already, being separated by their works?

The verse in Corinthians doesn’t mention “goats” because it doesn’t speak of condemnation. The message shows a distinction between those who have done the will of God – the works of the Holy Spirit vs. those who barely make it, because they didn’t receive the Holy Spirit to do those works (teaching by the Spirit, healing, discernment, casting out demons, speaking in tongues & interpretations, prophesying, miracles).

Only 144,000 receive the Holy Spirit (from the beginning of times until Jesus Christ returns). They will be given immortal bodies and rule with Christ because the are Chosen by God for a specific purpose.

Those who barely make it will be saved, but still as humans on new earth. So their reward is not as great as those who got chosen and dedicated their lives (gave up on worldly possessions, families, endured persecution, etc). Being chosen is being radical. It’s not your average career-seeking Christians that drive luxury cars to their church, live comfortably and never make any sacrifices. It’s a slippery slope to be on because there is no guarantee.

Having been baptized with the Holy Spirit is the guarantee of having received the ETERNAL LIFE and the choice of who to baptize belongs to God.

1 Corinthians‬ 3‬:11‬-15 “For no one can lay any foundation other than the one we already have—Jesus Christ. Anyone who builds on that foundation may use a variety of materials—gold, silver, jewels, wood, hay, or straw. But on the judgment day, fire will reveal what kind of work each builder has done. The fire will show if a person’s work has any value. If the work survives, that builder will receive a reward. But if the work is burned up, the builder will suffer great loss. The builder will be saved, but like someone barely escaping through a wall of flames.”

• The burned up work means they tried to do “works” by their human effort instead, but it’s worthless. God knows whom He chooses to work through. He also said that not many should become teachers in church, and yet, many act as if they were given that task (James 3:1)
• Those who do works by the Holy Spirit won’t be burned up because the Spirit is fire and lives within them because they were baptized with the Spirit (Psalms 21:9, Hebrews 12:29, Isaiah 43:1–7, Mark 1:8, Luke 3:16)

Isaiah‬ 65‬:17‬-22‬ “Look! I am creating new heavens and a new earth, and no one will even think about the old ones anymore. Be glad; rejoice forever in my creation! And look! I will create Jerusalem as a place of happiness. Her people will be a source of joy. I will rejoice over Jerusalem and delight in my people. And the sound of weeping and crying will be heard in it no more. No longer will babies die when only a few days old. No longer will adults die before they have lived a full life. No longer will people be considered old at one hundred! Only the cursed will die that young! In those days people will live in the houses they build and eat the fruit of their own vineyards. Unlike the past, invaders will not take their houses and confiscate their vineyards.
For my people will live as long as trees, AND my chosen ones will have time to enjoy their hard-won gains.”

*trees do not live forever.