Forgiveness in al-Islam
Does Allah Forgive Everything?
I’ve read that Allah forgives everything when you ask
Correct.
From Qur’an
“But whosoever repents after his crime and does righteous good deeds (by obeying Allah), then verily, Allah will pardon him (accept his repentance). Verily, Allah is Oft Forgiving, Most Merciful”
—Qur’an (al-Ma’idah) 5:39
“And He it is Who accepts repentance from His slaves, and forgives sins, and He knows what you do”
—Qur’an (ash-Shuraa) 42:25
“Say: O ‘Ibadi (My slaves) who have transgressed against themselves (by committing evil deeds and sins)! Despair not of the Mercy of Allah, verily, Allah forgives all sins. Truly, He is Oft-Forgiving, Most Merciful”
—Qur’an (az-Zumar) 39:53
“And whoever does evil or wrongs himself but afterwards seeks Allah’s forgiveness, he will find Allah Oft Forgiving, Most Merciful”
—Qur’an (an-Nisa) 4:110
From Ahadith
The Prophet (ﷺ) said: “Allah spreads out His Hand at night to accept the repentance of those who did wrong during the day, and He spreads out His Hand during the day to accept the repentance of those who did wrong during the night. (This will continue) until the sun rises from the west.”
The Prophet (ﷺ) said: “Our Lord comes down to the lowest heaven when one-third of the night remains, and says, ‘Who will call upon Me so that I may answer him? Who will ask Me so that I may give to him? Who will seek My forgiveness so that I may forgive him?'”
Anas bin Malik narrated that the Messenger of Allah (ﷺ) said: “Allah, Blessed is He and Most High, said: ‘O son of Adam! Verily as long as you called upon Me and hoped in Me, I forgave you, despite whatever may have occurred from you, and I did not mind. O son of Adam! Were your sins to reach the clouds of the sky, then you sought forgiveness from Me, I would forgive you, and I would not mind. So son of Adam! If you came to me with sins nearly as great as the earth, and then you met Me not associating anything with Me, I would come to you with forgiveness nearly as great as it.'”
RasoolAllah (ﷺ) said, “The one who repents from sin is like one who did not sin.”
—Sunan ibn Majah 4250, classed as Sahih by Shaykh al-Albani
What About Shirk?
but if you die in shirk, he does not.
Correct.
From Qur’an
“Indeed, he who associates others with Allah—Allah has forbidden him Paradise, and his refuge is the Fire. And there are not for the wrongdoers any helpers.”
—Qur’an (al-Ma’idah) 5:72
“Surely, disbelievers are those who said: ‘Allaah is the third of the three (in a Trinity).’ But there is no Ilaah (god) (none who has the right to be worshipped) but One Ilaah (God—Allaah). And if they cease not from what they say, verily, a painful torment will befall on the disbelievers among them.”
—Qur’an (al-Ma’idah) 5:73
“Indeed, Allah does not forgive association with Him, but He forgives what is less than that for whom He wills. And he who associates others with Allah has certainly fabricated a tremendous sin.”
—Qur’an (an-Nisa) 4:48
The Power of the Shahada
I’ve read that when someone says the shahada they are forgiven everything from before
Correct.
From Qur’an
“Say to those who have disbelieved, if they cease (from disbelief), their past will be forgiven”
—Qur’an (al-Anfal) 8:3
From Hadith
As the Prophet (ﷺ) said to ‘Amr ibn al-‘Aas (radhiAllah anhu): “O ‘Amr, do you not know that Islam wipes out whatever came before it.”
—Sahih Muslim 121, Musnad Ahmad 17861
Apostating & Returning
but what if they leave then come back? When they say the shahada again, is it like they have started all over?
The door of repentance is open for any and all sins, for any and every individual until death comes to him or the sun rises from the west (sign of the start of the Final Hour). Here’s a concise explanation of this.
But one shouldn’t get lax as a result of this mercy, as Allah tells us in the Qur’an:
“And of no effect is the repentance of those who continue to do evil deeds until death faces one of them and he says: ‘Now I repent;’ nor of those who die while they are disbelievers. For them We have prepared a painful torment”
—Qur’an (an-Nisa) 4:18
The Shahada in the Prayer
What about when a Muslim prays and the shahada is in the prayer, does the Muslim go back to being sinless again?
Allahu ‘alim on that, I don’t know I wouldn’t think so, because the wording of the hadith speaks about the slate being wiped clean for one entering into al-Islam, not the Shahada itself. I’ve also not heard any scholars or students of knowledge extrapolate such a meaning. I’m not myself a person of knowledge, so I can’t say one way or the other, though.
The Virtues of Wudu
I’ve also read that wudu washes away sins, is that true?
Yes.
From Ahadith
Abu Umamah reported: The Messenger of Allah (ﷺ) said, “Whenever a man performs his ablution intending to pray and he washes his hands, the sins of his hands fall down with the first drop. When he rinses his mouth and nose, the sins of his tongue and lips fall down with the first drop. When he washes his face, the sins of his hearing and sight fall down with the first drop. When he washes his arms to his elbows and his feet to his ankles, he is purified from every sin and fault like the day he was born from his mother. If he stands for prayer, Allah will raise his status by a degree. If he sits, he will sit in peace.”
In another narration, the Prophet (ﷺ) said, “When a Muslim man performs ablution, his sins are removed from his hearing, his sight, his hands, and his legs. If he sits down, he will sit down forgiven.”
—Musnad Ahmad 21680
Note that although it says "man" and "Muslim man," this is not a virtue which is exclusive to males; rather, it applies to both men and women, without any change in reward.
Saying "Astaghfirullah"
when someone says Astagfirullah, are they forgiven? Or when in prayer you say Astagfirullah?
I’m not 100%, I believe so, but there are conditions. The podcast I linked to you in a previous response went into detail on istighfar (seeking forgiveness) and how that differs from tawbah (repentance), the conditions of tawbah, etc. Did you get a chance to go through it?