We believe in the Last Day. It is one of the six pillars of faith mentioned in the verse that reads: {It is not righteousness to turn your faces towards the east or the west, but righteousness is to believe in Allah and the Last Day.} [Surat al-Baqarah: 177] And the verse that reads: {But those well-grounded in knowledge among them and the believers believe in what has been sent down to you [O Prophet], and what was sent down before you; who establish prayer and give Zakah, and believe in Allah and the Last Day – it is they who We will give a great reward.} [Surat an-Nisā’: 162]
It is also established by a Hadīth in which Abu Hurayrah (may Allah be pleased with him) reported: The Messenger of Allah (may Allah’s peace and blessings be upon him) came out to people one day, and someone came to him and said: "O Messenger of Allah, what is faith?" He replied: "It is to believe in Allah and His angels, His book, the meeting with Him, and His messengers, and believe in the Resurrection in the Afterlife." [Narrated by Al-Bukhāri (4777), Muslim (9), and Ibn Mājah (64)]
It is also established by reason. Allah, Exalted be He, says: {And he produced arguments against Us while forgetting his own creation. He says: "Who can give life to the bones after they have crumbled to dust?" Say: "The One Who created them in the first place will give life to them, for He has full knowledge of every created being."} [Surat Yāsīn: 78-79] He Almighty also says: {O mankind, if you are in doubt concerning the Resurrection, then We surely created you from dust, then from a drop of sperm, then from a clot, then from a lump of flesh – formed or unformed – so that We may make it clear to you [Our power]. We settle in the wombs whatever We will for an appointed term. Then We bring you out as infants, then [We nurture you] so that you may reach your maturity. Then some of you die, while others are left to reach the decrepit old age so that they may know nothing after having knowledge. You see the land lifeless, then as soon as We send down rain on it, it stirs and swells to life and brings forth every type of pleasant plant.} [Surat al-Hajj: 5] In another verse, Allah, the Exalted, says: {Are you more difficult to create or the heaven that He built?} [Surat an-Nāzi‘āt: 27] And He, Glorified be He, says: {And among His signs is that you see the land withered, but when We send down rain upon it, it stirs and swells. He Who gives it life will surely give life to the dead, for He is Most Capable of all things.} [Surat Fussilat: 39] Allah Almighty also says: {It is He Who originates the creation then repeats it, which is easier for Him.} [Surat ar-Rūm: 27] And He, Exalted be He, says: {Just as We originated the first creation, so We will bring it back. That is Our binding promise, which We will surely do.} [Surat al-Anbiyā’: 104]
It is called the Last Day because it will be the last day in this world. No day will follow it. It also has numerous other names. Its names include the Day of Judgment, the Day of Resurrection, the Day of Reckoning, the Day of Recompense, At-Tāmmah (the Supreme Calamity), Al-Hāqqah (the Inevitable Hour), Al-Wāqi‘ah (the Inevitable Event), As-Sākhkhah (the Deafening Blast), and Al-Ghāshiyah (the Overwhelming Event). Allah Almighty mentions the Last Day in many verses of His noble Book. Examples include the verse that says: {A Day when people will stand before the Lord of the worlds.} [Surat al-Mutaffifīn: 6] And the verse that reads: {The Day when they will rush out of their graves as if they are racing towards a goal.} [Surat al-Ma‘ārij: 43] And the verse that reads: {But when the Supreme Calamity comes.} [Surat an-Nāzi‘āt: 34] And the verses that read: {But when the Deafening Blast comes, on that Day everyone will flee from his sibling, and from his mother and father, and from his wife and children. On that day, everyone will have enough concern of his own.} [Surat ‘Abasa: 33-37] And the verses that read: {O mankind, fear your Lord; the earthquake of the Hour is something dreadful. On the Day when you see it, every nursing mother will abandon her baby, and every pregnant woman will miscarry. You will see people as though they are drunk, while they are not drunk, but the punishment of Allah is severe.} [Surat al-Hajj: 1-2] And the verse that reads: {When He will gather you for the Gathering Day; that is the Day of great loss.} [Surat at-Taghābun: 9]