Surah Ali 'Imran 3:85

وَمَن يَبْتَغِ غَيْرَ ٱلْإِسْلَـٰمِ دِينًا فَلَن يُقْبَلَ مِنْهُ وَهُوَ فِى ٱلْـَٔاخِرَةِ مِنَ ٱلْخَـٰسِرِينَ

And whoever desires other than Islām as religion - never will it be accepted from him, and he, in the Hereafter, will be among the losers.

Translation: Saheeh International

Tafsir

The following was revealed regarding those who apostatized and became disbelievers Whoever desires a religion other than Islam it shall not be accepted from him and in the Hereafter he shall be among the losers because he will end up in the Fire made everlasting for him.

Excerpt from Tafsir al-Jalalayn, commentary on 3:85, via Quran.com. The reader has the full commentary and 9 more tafsirs.