Short answer
Islam teaches that belief in a Creator is part of human nature, and the Quran invites atheists to reflect: were they created by nothing, or did they create themselves? Denying Allah is disbelief, but an atheist has the same right to kindness, justice and safety as any other non-Muslim, and no one may be forced to believe.
Denying the existence of Allah is kufr. In dealings, an atheist is treated like any other non-Muslim: their life, property and dignity are protected, good neighbourliness and kindness are encouraged, and they may not be compelled into Islam. A Muslim may not marry an atheist, since only People of the Book are allowed in marriage, and only for men.
The four schools agree on this.
Explanation
The Quran says Allah created people upon the fitrah, a natural awareness of Him, and the Prophet ﷺ said every child is born upon it. Islam therefore sees atheism not as a neutral starting point but as a covering over of something already inside a person. Even so, Islam does not respond with force: "there shall be no compulsion in religion."
The Quran engages the atheist's question directly, with reasoning rather than threats: "Or were they created by nothing, or were they the creators of themselves? Or did they create the heavens and the earth?" It points again and again to the signs in creation and within ourselves, and invites people to think. Muslims are told to invite "with wisdom and good instruction".
- Atheist family: parents keep their full rights to kindness and care. See non-Muslim parents.
- Friends and colleagues: friendship, honesty and good manners are fine. See friendship with non-Muslims.
- Discussions: share your reasons calmly. Insults and point scoring push people away.
- Your own doubts: questions are normal. Bring them to a knowledgeable person rather than hiding them, and keep praying while you look for answers.
On what happens in the Hereafter, see do non-Muslims go to heaven? On the existence of Allah, see who is Allah and tawheed.
The evidence
Quran, Surah At-Tur 52:35-36
أَمْ خُلِقُوا۟ مِنْ غَيْرِ شَىْءٍ أَمْ هُمُ ٱلْخَٰلِقُونَ ﴿٣٥﴾ أَمْ خَلَقُوا۟ ٱلسَّمَٰوَٰتِ وَٱلْأَرْضَ ۚ بَل لَّا يُوقِنُونَ ﴿٣٦﴾
Or were they created by nothing, or were they the creators [of themselves]? Or did they create the heavens and the earth? Rather, they are not certain.
The Quran reasons with those who deny a Creator.
Quran, Surah Ar-Room 30:30
فَأَقِمْ وَجْهَكَ لِلدِّينِ حَنِيفًۭا ۚ فِطْرَتَ ٱللَّهِ ٱلَّتِى فَطَرَ ٱلنَّاسَ عَلَيْهَا ۚ لَا تَبْدِيلَ لِخَلْقِ ٱللَّهِ ۚ ذَٰلِكَ ٱلدِّينُ ٱلْقَيِّمُ وَلَٰكِنَّ أَكْثَرَ ٱلنَّاسِ لَا يَعْلَمُونَ ﴿٣٠﴾
So direct your face toward the religion, inclining to truth. [Adhere to] the fitrah of Allah upon which He has created [all] people. No change should there be in the creation of Allah. That is the correct religion, but most of the people do not know.
Awareness of the Creator is part of human nature.
Quran, Surah Al-Baqara 2:256
لَآ إِكْرَاهَ فِى ٱلدِّينِ ۖ قَد تَّبَيَّنَ ٱلرُّشْدُ مِنَ ٱلْغَىِّ ۚ فَمَن يَكْفُرْ بِٱلطَّٰغُوتِ وَيُؤْمِنۢ بِٱللَّهِ فَقَدِ ٱسْتَمْسَكَ بِٱلْعُرْوَةِ ٱلْوُثْقَىٰ لَا ٱنفِصَامَ لَهَا ۗ وَٱللَّهُ سَمِيعٌ عَلِيمٌ ﴿٢٥٦﴾
There shall be no compulsion in [acceptance of] the religion. The right course has become clear from the wrong. So whoever disbelieves in Taghut and believes in Allah has grasped the most trustworthy handhold with no break in it. And Allah is Hearing and Knowing.
No one may be forced into belief.
Quran, Surah An-Nahl 16:125
ٱدْعُ إِلَىٰ سَبِيلِ رَبِّكَ بِٱلْحِكْمَةِ وَٱلْمَوْعِظَةِ ٱلْحَسَنَةِ ۖ وَجَٰدِلْهُم بِٱلَّتِى هِىَ أَحْسَنُ ۚ إِنَّ رَبَّكَ هُوَ أَعْلَمُ بِمَن ضَلَّ عَن سَبِيلِهِۦ ۖ وَهُوَ أَعْلَمُ بِٱلْمُهْتَدِينَ ﴿١٢٥﴾
Invite to the way of your Lord with wisdom and good instruction, and argue with them in a way that is best. Indeed, your Lord is most knowing of who has strayed from His way, and He is most knowing of who is [rightly] guided.
Muslims discuss faith with wisdom and good manners.
Sahih al-Bukhari 1358
Sahih... ما من مولود إلا يولد على الفطرة ...
"Every child is born upon the fitrah."
Belief in the Creator is the natural state every person starts from.
Where the ruling is recorded
- al-Hidaya, Kitab al-Nikah, the section on the women one may not marry. Only women of the People of the Book are permitted among non-Muslims, which excludes a person with no religion.
Checked by our team. For a more accurate answer to your own situation, consult a scholar. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.