The Universalists I’ve spoken with believe everyone - including satan - will be saved.
They claim the second death is not an eternal punishment in Hell, but “a judgment that results in the saving of all”. (The Lake of Fire, part Three", paragraph six)
In other words, the sacrifice of Jesus intended to save the entire world, was a failure because some people rejected Jesus. Since God cannot fail an alternative means for salvation was needed to save those who Jesus lost.
To Universalists, the second death is where those who rejected Jesus are beat into submission. When those who reject Jesus cannot take the punishment anymore they confess Jesus and are allowed entry into heaven. This is the judgment that results in the saving of all.
Of course this disagrees with the Holy Scriptures which state Jesus Christ is the ONLY way to salvation:
John 14:6 Jesus answered, “No one comes to the Father except through me.”
It also disagrees with the Holy Scriptures which states not everyone will received eternal life.
Matthew 10:28, Jesus said, “And fear not them which kill the body, but are not able to kill the soul: but rather fear him which is able to destroy both soul and body in hell.”
Romans 6:23: For the wages of sin is death:
Psalm 73:27 “Those who are far from you will perish; You destroy all who are unfaithful to you.”
Mal 4:3 “…they will be ashes under your feet.”
Prov 10:7 “… the name of the wicked will rot”.
If you are looking to discuss their “faith” I think your best defense is to use the Scriptures.
Ginger