The one who dies not associating anything with Allah will enter Paradise, and the one who dies associating something with Allah will enter Hell
Question

I have a question about verses 68-69 of Soorat al-Furqaan, which speak about the crimes of shirk (associating others with Allah) and zina (fornication or adultery), and their punishment and consequences. In Soorat an-Nisa’ 4:48, it says that shirk is the only sin that will not be forgiven. I would like clarification: is there a contradiction here? Because it is mentioned alongside the sin of zina in Soorat al-Furqaan and is subject to punishment, but in Soorat an-Nisa’ the punishment is mentioned for the sin of shirk only, whilst other sins remain subject to the will of Allah, and He will forgive whomever He wills.
Praise be to Allah.We ask Allah to help you to obey Him and to make it easy for you to call people to His religion.
With regard to what you have asked about, there is no contradiction, praise be to Allah. Allah, may He be exalted, says in Soorat an-Nisa’ (interpretation of the meaning):
{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} [an-Nisa’ 4:48].
And He, may He be glorified, says (interpretation of the meaning):
{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 gone far astray} [an-Nisa’ 4:116].
And He, may He be glorified, says in Soorat al-Furqaan (interpretation of the meaning):
{And those who do not invoke with Allah another deity or kill the soul which Allah has forbidden [to be killed], except by right, and do not commit unlawful sexual intercourse. And whoever should do that will meet a penalty.
Multiplied for him is the punishment on the Day of Resurrection, and he will abide therein humiliated,
Except for those who repent, believe and do righteous work. For them Allah will replace their evil deeds with good. And ever is Allah Forgiving and Merciful.
And he who repents and does righteousness does indeed turn to Allah with [accepted] repentance} [al-Furqaan 25:68-71].
What is mentioned in Soorat an-Nisa’ has to do with one who dies associating others with Allah without having repented from that in the life of this world. The one who meets Allah associating others with Him is the one whom Allah will not forgive. This punishment is being deprived of forgiveness forever pertaining to this sin, namely dying associating others with Allah, may He be exalted.
With regard to what is mentioned in Soorat al-Furqaan about the one who associates others with Allah, or commits major sins that doom a person to Hell, the one who does any of those things, then repents from that before death catches up with him, Allah will turn to him in mercy and forgive his sin. Thus these people who associated others with Allah or committed any of the other major sins mentioned have two things in common:
Firstly: for the one who does that, Allah warn him of punishment in the fire of Hell, as a requital for his sin, whether that sin of his was associating others with Allah (shirk) or any other sin.
Secondly: for the one who repents before he dies, Allah will turn to him in mercy and forgive him his sin, by His grace and mercy, because Islam erases what came before it, and repentance erases what came before it. Allah, may He be exalted, says (interpretation of the meaning):
{Say to those who have disbelieved [that] if they cease, what has previously occurred will be forgiven for them } [al-Anfaal 8:38].
From what we have mentioned above, we may understand several things:
Firstly: that the one who dies associating anything with Allah, Allah will forbid Paradise to him, and his abode will be Hell.
Secondly: that whoever repents, Allah will turn to him in mercy, even if he had associated others with Him or had committed any other major sins.
Thirdly: If someone who committed major sins dies, but he did not associate anything with Allah, then he is subject to the will of Allah: if He wills He will punish him, and if He wills He will forgive him. But if He punishes him, he will not abide forever in Hell; rather his ultimate destiny will be Paradise.
Al-Bukhaari (4810) and Muslim (122) narrated from Ibn ‘Abbaas (may Allah be pleased with him) that some of the polytheists killed and did it a great deal, and they committed zina and did it a great deal. Then they came to Muhammad (blessings and peace of Allah be upon him) and said: What you are saying and are calling to is good, if only you could tell us that there is any expiation for what we have done. Then the words were revealed: {And those who do not invoke with Allah another deity or kill the soul which Allah has forbidden [to be killed], except by right, and do not commit unlawful sexual intercourse} [al-Furqaan 25:68] and {Say, “O My servants who have transgressed against themselves [by sinning], do not despair of the mercy of Allah”} [al-Zumar 39:53].
At-Tirmidhi (3540) narrated, and classed the report as hasan, that Anas ibn Maalik said: I heard the Messenger of Allah (blessings and peace of Allah be upon him) say: “Allah, may He be blessed and exalted, says: ‘O son of Adam, if your sins were to reach the clouds of the sky, then you were to ask Me to forgive you, I would forgive you and I would not mind. O son of Adam, if you were to come to me with an earthful of sins, then you were to meet Me not associating anything with Me, I would come to you with an earthful of forgiveness.” Classed as saheeh by al-Albaani in Saheeh at-Tirmidhi.
Al-Bukhaari (1238) and Muslim narrated that Ibn Mas‘ood (may Allah be pleased with him) said: The Messenger of Allah (blessings and peace of Allah be upon him) said: “ Whoever dies associating anything with Allah will enter Hell.”
Muslim (93) narrated that Jaabir said: A man came to the Prophet (blessings and peace of Allah be upon him) and said: O Messenger of Allah, what are the two things that decide a person’s fate? He said: “Whoever dies not associating anything with Allah will enter Paradise, and whoever dies associating anything with Allah will enter Hell.”
Ash-Shawkaani (may Allah have mercy on him) said:
There is no difference of opinion among the Muslims concerning the fact that if the polytheist dies associating others with Allah, he will not be forgiven in a way in which Allah may forgive those who do not associate others with Him, in accordance with His will and decree. As for those who do not associate others with Allah of the sinners among the Muslims, they are subject to the will of Allah; He will forgive whomever He wills and He will punish whomever He wills." (Fath al-Qadeer  1/717).
He also said:
If one who associates others with Allah repents, Allah will forgive him for what he did of associating others with Him, according to the consensus of the Muslims." (Fath al-Qadeer  4/667).
For more information, please see the answers to questions no. 31174 and 34171 .
And Allah knows best.