Praise be to Allah.
What is meant by belief in the Last Day is:
Firmly believing that everything that Allaah has told us about in His Book and that His Messenger (peace and blessings of Allaah be upon him) has told us about what will happen after death, will indeed happen and come to pass. That includes believing in the signs of the Hour which will happen before the Last Day; in death and things that accompany it when a person is on his deathbed; what comes after death, namely the trial of the grave and torment or blessing therein; the Trumpet-blast and resurrection; the standing and terrors of the Day of Resurrection; the details of the gathering and reckoning; Paradise and its delights, the greatest of which will be looking upon the Face of Allaah; Hell and its torments, the most severe of which will be their being veiled from seeing their Lord. And belief in the Last Day includes acting in accordance with what is implied by these beliefs.
If this belief is firmly established in a person’s heart, it will bear great fruits, including the following:
1 – The desire to do acts of obedience and worship, and to strive hard in doing so, in the hope of attaining the rewards of that Day.
2 – Fear of committing sin or approving of it, for fear of the punishment of that Day.
3 – The believer will be consoled for whatever he misses out on of worldly luxuries and delights, because of his hope for the delights and rewards of the Hereafter.
We ask Almighty Allaah to bless us with sincere belief and unshakeable certainty of faith… Ameen.
See A’laam al-Sunnah al-Manshoorah, 110; Sharh al-Usool al-Thalaathah by Shaykh Ibn ‘Uthaymeen, 98-103.