Hello Designs,
the notion of eternal punishment is the central ethical idea of the Trinity God, it is its main ethical flaw
Belief in the Trinity has nothing to do with the "notion of eternal punishment". There are Trinitarians who believe in annihilationism.
Those who believe that eternal punishment is only a "notion" but believe eternal blessing is not a notion pick and choose from the bible, even from the same verse! Here's some examples.
Daniel 12:2 (New International Version)
2 Multitudes who sleep in the dust of the earth will awake: some to everlasting life, others to shame and everlasting contempt.
Matthew 25:46 (New International Version)
46 "Then they will go away to eternal punishment, but the righteous to eternal life."
Acts 24:15 (New International Version)
15 and I have the same hope in God as these men, that there will be a resurrection of both the righteous and the wicked.
As it is written, let God be true and every man a liar Romans 3:4
All the best,
Stephen