Al-Baqarah 2:28

How can you disbelieve in Allah seeing that you were dead and He gave you life? Then He will give you death, then again will bring you to life (on the Day of Resurrection) and then unto Him you will return (28)

Allah testifies to the fact that He exists and that He is the Creator and the Sustainer Who has full authority over His servants,

كَيْفَ تَكْفُرُونَ بِاللَّهِ

(How can you disbelieve in Allah?)

How can anyone deny Allah's existence or worship others with Him while;

وَكُنتُمْ أَمْوَاتًا فَأَحْيَاكُمْ

(You were dead and He gave you life) meaning, He brought them from the state of non-existence to life. Similarly, Allah said,

أَمْ خُلِقُوا مِنْ غَيْرِ شَيْءٍ أَمْ هُمُ الْخَالِقُونَ - أَمْ خَلَقُوا السَّمَاوَاتِ وَالْأَرْضَ بَل لَّا يُوقِنُونَ

(Were they created by nothing? Or were they themselves the creators? Or did they create the heavens and the earth? Nay, but they have no firm belief)(52:35-36) and,

هَلْ أَتَىٰ عَلَى الْإِنسَانِ حِينٌ مِّنَ الدَّهْرِ لَمْ يَكُن شَيْئًا مَّذْكُورًا

(Has there not been over man a period of time, when he was not a thing worth mentioning?)(76:1).

There are many other Ayat on this subject. Ibn Jarir reported from 'Ata' that Ibn 'Abbas said that,

وَكُنتُمْ أَمْوَاتًا فَأَحْيَاكُمْ

(Seeing that you were dead and He gave you life) means, "You did not exist beforehand. You were nothing until Allah created you; He will bring death to you and then bring you back to life during Resurrection." Ibn 'Abbas then said, "This is similar to Allah's statement;

قَالُوا رَبَّنَا أَمَتَّنَا اثْنَتَيْنِ وَأَحْيَيْتَنَا اثْنَتَيْنِ

(They will say: "Our Lord! You have made us to die twice and You have given us life twice.")(40:11)"