Assalaamu'Alaykum,
You should use the numerous verse's of the Qur'aan in order to answer your friend.
For example:
"O' mankind! Worship your Lord [Allah], Who created you and those who were before you so that you may become Al-Muttaqoon.
Who has made the earth a resting place for you, and the sky as a canopy, and sent down water [rain] from the sky and brought forth therewith fruits as a provision for you. Then do not set up rivals unto Allah [in worshp] while you know [that He Alone has the right to be worshipped].
[Qur'aan 2: 21-22]
O' mankind! Remember the Grace of Allah upon you! Is there any creator other than Allah who provides for you from the sky [rain] and the earth? Laa ilaaha illa Huwa [none has the right to be worshipped but He]. How then are you turning away [from Him]?
[Qur'aan 35: 3]
He has created the heavens without any pillars that you see, and has set on the earth firm mountains lest it should shake with you. And He has scattered therein moving [living] creatures of all kinds. And We send down water [rain] from the sky, and We cause [plants] of every goodly kind to grow therein.
This is the creation of Allah. So show Me that which those [whom you worship] besides Him have created. Nay, the Zaalimoon [polythiests, wrongdoers and those who do not believe in the Oneness of Allah] are in plain error.
[Qur'aan 31: 10-11]
"He has created the heavens and the earth with truth. He makes the night to go in the day and makes the day to go in the night. And He has subjected the sun and the moon. Each running [on a fixed course] for an appointed term. Verily, He is the All-Mighty, the Oft-Forgiving.
He created you [all] from a single person [Adam]; then made from his wife [Hawwa (Eve)]. And He has sent down for you of cattle eight pairs [of the sheep, two, male and female; of the goats, two, male and female; of the oxen, two, male and female; and of the camels, two, male and female.] He creates you in the wombs of your mothers, creation after creation in three veils of darkness. Such is Allah your Lord. His is the kingdom. Laa ilaaha illa Huwa [none has the right to be worshipped but He]. How then are you turned away?
[Qur'aan 39: 5-6]
Have not those who disbelieve known that the heavens and the earth were joined together as one united piece, then We parted them? And We have made from water every living thing. Will they not then believe?
And We have placed on the earth firm mountains, lest it should shake with them, and We placed therein broad highways for them to pass through, that they may be guided.
And We have made the heaven a roof, safe and well-guarded. Yet they turn away from its signs [i.e. sun, moon, winds, clouds, etc.].
And He it is Who has created the night and the day, and the sun and the moon, each in an orbit floating.
[Qur'aan 21: 30-33]
Say (O Muhammad ): "Praise and thanks be to Allâh, and peace be on his slaves whom He has chosen (for his Message)! is Allâh better, or (all) that You ascribe as partners (to Him)?" (of course, Allâh is Better).
Is not He (better than Your gods) who created the heavens and the earth, and sends down for You water (rain) from the sky, whereby we Cause to grow wonderful Gardens full of beauty and delight? it is not In Your ability to Cause the growth of their trees. is there any Ilâh (God) with Allâh? Nay, but they are a people who ascribe equals (to him)!
Is not He (better than Your gods) who has made the earth as a fixed abode, and has placed rivers In its midst, and has placed firm mountains therein, and has set a barrier between the two seas (of salt and sweet water).Is there any Ilâh (God) with Allâh? Nay, but Most of them know not.
Is not He (better than Your gods) who responds to the distressed one, when He calls him, and who removes the evil, and makes You inheritors of the earth, generations after generations. is there any Ilâh (God) with Allâh? little is that You remember!
Is not He (better than Your gods) who guides You In the darkness of the land and the sea, and who sends the winds as heralds of glad tidings, going before his Mercy (rain)? is there any Ilâh (God) with Allâh? High Exalted be Allâh above All that they associate as partners (to him)!
Is not He (better than Your so-called gods) who originates creation, and shall thereafter repeat it, and who provides for You from heaven and earth? is there any Ilâh (God) with Allâh? say, "Bring forth Your proofs, if You are truthful."
[Qur'aan 27: 59-64]
...Can there be a doubt about Allah, the Creator of the heavens and the earth? He calls you [to Monotheism and to be obedient to Allah] tha He may forgive you of your sins...
[Qur'aan 14: 10]
Question him in relation to his disbelief, from the Qur'aan:
"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."
[Qur'aan 2: 28]
"O' man! What has made you careless about your Lord, the Most Generous? Who created you, fashioned you perfectly, and gave you due proportion. In whatever form He willed, He put you together."
[Qur'aan 82: 6-8]
"What is the matter with you, that [you fear not Allah (His punishment), and] you hope not for reward [from Allah or you believe not in His Oneness]. While He has created you in [different] stages [i..e first Nutfah, then 'Alaqah and then Mudghah]. See you not how Allah has created the seven heaves one above another? And has made the moon a light therein, and made the sun a lamp? And Allah has brought you forth from the [dust of] earth? Afterwards He will return you into it [the earth] and bring you forth [again on the Day of Resurrection]?
[Qur'aan 71: 13-18]
There is a good book titled "Belief in Allah by Umar Sulaymaan Al-Ashqar" which is excellent for both Muslims and non-Muslims. The link is below for a short description and another link in which i created a thread as i posted little bits from it but i did not post the portions in relation to refuting Darwin's theory, that Nature is the Creator or the view that is happend by accident.
http://www.salafibookstore.com/sbs/index.cfm?scn=books&ProductID=B492&do=detail&book=http://www.turntoislam.com/forum/showthread.php?t=38089
Oh, i nearly forgot, i created a separate thread for
Aqeedah vs Philosophy & Ilm-al-Kalaam, link is below:
http://www.turntoislam.com/forum/showthread.php?t=38442
Insha'Allaah this will help in some way -
if it is too much, just use the aayaat of the Qur'aan, i only included the links to the thead's so that you could check what is in the book and whether it would be helpful or not - as stated, certain portions i have not added.
Walaykum Salaam.