First of all Jesus IS God, no-one delivered Jesus from anywhere, he Himself did all the delivering. “Freely I lay down my life, and freely I take it up again” as He says in the Gospels.
Secondly, Jesus made clear that damnation is indeed forever. In the Gospel story of the rich man and Lazarus Our Lord made clear that the rich man was irredeemably damned in spite of his pleading, and separated by ‘an impassable gulf’ from Abraham, Lazarus and all the souls of the righteous.
Thirdly, Jesus never went to hell of the eternally damned. The original word used simply means ‘afterlife’, not ‘hell’ in the sense we understand it.
He DID go to ‘the dead’ (as some translations of the Apostle’s Creed put it) - but only the righteous dead. They, as opposed to the damned, were living in what is called the ‘Bosom of Abraham’, a limbo state, where they awaited Christ’s passion ad resurrection to redeem them. Again the story of the rich man and Lazarus shows this.
As for atheists - we can only leave them, as we leave all souls of whose fate we are uncertain, to the mercy of God, who alone completely knows their minds and hearts well enough to judge righty.