๐๐ฌ ๐ญ๐ก๐๐ซ๐ ๐ ๐๐ข๐ฌ๐๐ซ๐๐ฉ๐๐ง๐๐ฒ ๐๐๐ญ๐ฐ๐๐๐ง ๐๐ฎ๐ซ๐๐ง (๐๐:๐๐) ๐๐ง๐ ๐๐ฎ๐ซ๐๐ง (๐:๐๐)?
Mohamad Mostafa Nassar
Twitter:@NassarMohamadMR
Allegation:
The Quran 4:48 says that sin of โshirkโ or associating partner with God will not be forgiven, but 39:53 says that all sins will be forgiven. So, there is a contradiction.
The two verses are talking to the different audiances. Read some preceding verses, you will figure out that to whom these verses are directed.
Quran (4:48) about to People of The Book:
4:48 is talking to the people of the book (read the previous verse 4:47). Some of them (not all) used to believe in superstition, magic and power of evil, as said in few verses later (4:51). It deviated them from monotheism described in their original scripture (Torah). Thus, Quran (4:48) is warning them about it.
“Hast thou not turned Thy vision to those who were given a portion of the Book? they believe in sorcery and Evil, (Taghut)โ Quran (4:51).
Here the Noble Quranic Verses from (4:47-51)



โโฆAnd when there came to them an apostle from God, confirming what was with them, a party of the people of the Book threw away the Book of God behind their backs, as if (it had been something) they did not know! They followed what the evil ones gave out (falsely) against the power of Solomon: (black magic)โฆโ(2:101โ2).
Here the Noble Quranic Verses from (2:101-102)


O ye People of the Book! believe in what We have (now) revealed, confirming what was (already) with youโฆGod forgiveth not that partners should be set up with Him; but He forgiveth anything else, to whom He pleaseth; to set up partners with God is to devise a sin Most heinous indeed.. Quran (4:47โ48)

In other verses, people of the books were warned to not take Ezra or Jesus as son of God, but in this context it is talking about believing in superstition, magic (taghut) etc, which is considered as shirk.
Quran (39:53): Ibaddi=ุนุจุงุฏู=My Servants
On the other hand, Quran (39:53) starts with โmy servantsโ (โIbaadiโ). It’s already talking to the people who believe in wholesome submission toward the God alone, rejecting all โtaghutโ. Quran(39:53) is talking about the other sins he has committed and saying him to turn in repentance.

โDistinct has now become the right way from [the way of] error: hence, he who rejects โtaghutโ and believes in God has indeed taken hold of a support most unfailing..โ (Quran 2:256)

โSAY: [Thus speaks God: ] O you servants of Mine who have transgressed against your own selves! Despair not of Gods mercy: behold, God forgives all sins -for, verily, He alone is much-forgiving, a dispenser of grace! Quran (39:53).
โTurn to your Lord. Submit to Him before the punishment overtakes you and you can no longer be helped.โ (Quran 39:54).


Repentence
The following verses describe that if the people committing โshirkโ remain without repentance, their is no forgiveness and the penalty will be doubled. But if they repent, they will be forgiven. Note that, โshirkโ is not only polytheism but many other things such as believing in superstition.
Now in Quran (4:48), that particular group at some point of the history didn’t have any sign of repentance and has uncompromising attitude about โtaghutโ. That is why that verse was so harsh about them. God is merciful and he forgives all sins through repentance.

My โibaadiโ areโฆthose who never invoke another god alongside Godโฆwhoever does these things will face a penalty that will be multiplied for him on the Day of Resurrection, and he will remain in humiliation forever, except those who repent, believe and do righteous work, [in that case] God will replace their evil deeds with good ones for God is ever-forgiving and Merciful-to-all. (Quran 25:63โ71)
It is not right to pick just 2 random verses to point out contradiction. You need to look at the context, addressee and other verses of Quran describing similar topic to get an overall grasp on the message, before reaching that conclusion.
Allah knows Best.