Twice in the Quran, God explicitly condemns those who say that God is a trinity.
4:171 O people of the scripture, do not transgress the limits of your religion, and do not say about GOD except the truth. The Messiah, Jesus, the son of Mary, was a messenger of GOD, and His word that He had sent to Mary, and a revelation from Him. Therefore, you shall believe in GOD and His messengers. You shall not say, “Trinity.” You shall refrain from this for your own good. GOD is only one god. Be He glorified; He is much too glorious to have a son. To Him belongs everything in the heavens and everything on earth. GOD suffices as Lord and Master.
يَـٰٓأَهْلَ ٱلْكِتَـٰبِ لَا تَغْلُوا۟ فِى دِينِكُمْ وَلَا تَقُولُوا۟ عَلَى ٱللَّهِ إِلَّا ٱلْحَقَّ إِنَّمَا ٱلْمَسِيحُ عِيسَى ٱبْنُ مَرْيَمَ رَسُولُ ٱللَّهِ وَكَلِمَتُهُۥٓ أَلْقَىٰهَآ إِلَىٰ مَرْيَمَ وَرُوحٌ مِّنْهُ فَـَٔامِنُوا۟ بِٱللَّهِ وَرُسُلِهِۦ وَلَا تَقُولُوا۟ ثَلَـٰثَةٌ ٱنتَهُوا۟ خَيْرًا لَّكُمْ إِنَّمَا ٱللَّهُ إِلَـٰهٌ وَٰحِدٌ سُبْحَـٰنَهُۥٓ أَن يَكُونَ لَهُۥ وَلَدٌ لَّهُۥ مَا فِى ٱلسَّمَـٰوَٰتِ وَمَا فِى ٱلْأَرْضِ وَكَفَىٰ بِٱللَّهِ وَكِيلًا
5:73 Pagans indeed are those who say that GOD is a third in a trinity. There is no god except the one god. Unless they refrain from saying this, those who disbelieve among them will incur a painful retribution.
لَّقَدْ كَفَرَ ٱلَّذِينَ قَالُوٓا۟ إِنَّ ٱللَّهَ ثَالِثُ ثَلَـٰثَةٍ وَمَا مِنْ إِلَـٰهٍ إِلَّآ إِلَـٰهٌ وَٰحِدٌ وَإِن لَّمْ يَنتَهُوا۟ عَمَّا يَقُولُونَ لَيَمَسَّنَّ ٱلَّذِينَ كَفَرُوا۟ مِنْهُمْ عَذَابٌ أَلِيمٌ
One criticism of the Quran is that it does not explicitly specify the trinity as the Father, Son, and Holy Spirit, which is the most common claim by today’s pagan Christians. This is because, throughout Christian history, there have been various interpretations and alternative sets for the Trinity proposed by different groups and individuals. Here are some examples of other sets that have been considered in place of the traditional Father, Son, and Holy Spirit: