All perfect praise be to Allah the Lord of the Worlds. May His peace and blessings be upon our Prophet Mohammad and upon all his family and companions.

 

Ahlus Sunnah wal Jamaah believe that Paradise and Hell do  exist and even had existed before Adam and Eve were created:

Abu Al-Hasan al-`Ash`ari (May Allah have mercy on him) says: "They-Ahlus Sunnah wal Jamaah-confirm that Paradise and Hell exist." {Maqalat Al-Islamieen, P.296}.

He (May Allah have mercy on him) also said: "There is disagreement whether Paradise and Hell have been created or not?" Ahlus Sunnah wal Jamaah said that they have been created." However, many innovators said that they haven’t been created." {pp.475, Dar `Ehya` al-Torath Edition}. 

"The evidence on this is the story of Adam and Eve mentioned in the Glorious Quran where Almighty Allah said {What means}: "And We Said: ’Adam, dwell thou, and thy wife, in the Garden, and eat thereof easefully where you desire; but draw not nigh this tree, lest you be evildoers." {Al-Baqarah, 35}. The Garden, here, is an unconditional term referring to the eternal bliss that Allah promised the believers.

Moreover, many narrations confirm that Paradise and Hell exist. For example, Narrated `Abdullah bin `Umar: Allah's Messenger (Peace and blessings be upon him) said: "When anyone of you dies, he is shown his place both in the morning and in the evening. If he is one of the people of Paradise; he is shown his place in it, and if he is from the people of the Hell-Fire; he is shown his place there-in. Then it is said to him, 'This is your place till Allah resurrect you on the Day of Resurrection." {Agreed upon}.

These texts clearly indicate that Paradise and Hell existed before the Day of Resurrection, so there is no need to interpret them (texts) other than through their apparent meaning. Whoever denies this fact is merely chasing mirage since he/she is denying an unseen matter that has been established in Prophetic traditions." The above excerpt is copied from [Al-Mokhtasar Al-Mufeed Shareh Jawharat at-Tawheed, pp. 203-204]." by late Grand Mufti Dr. Nooh Salman Al-Qhodah. 

As for eternity, scholars from amongst the righteous successors and predecessors are agreed that the believers abide in paradise forever while the disbelievers abide in Hell forever. The evidence on this is that Almighty Allah Says {What means}: "Verily God has cursed the Unbelievers and prepared for them a Blazing Fire,- To dwell therein for ever: no protector will they find, nor helper." {Al-Ahzab, 64-65}.

Here, the wisdom behind the disbelievers` abiding in Hell forever is that had they been left alive forever they would have remained as disbelievers since Allah The Almighty Said {What means}: " Yea, in their own (eyes) will become manifest what before they concealed. But if they were returned, they would certainly relapse to the things they were forbidden, for they are indeed liars." {Al-An`am, 28}. And Allah The Almighty Knows Best.