Alaykum Salaam. Thank you for your question.
Your agnostic friend's conception of God is radically
different from the conception of God in Islam as a God who is intimately involved in
the creation, subsistence and destiny of all of His creatures. While God is powerful
to directly interfere in human action, He has also given the human free will and
consequently the human is responsible for his own actions as a test to show him
which path he will take in life. The human has to use all of his faculties to
understand the correct path, which is belief and worship of God, for his own
benefit. That is because God created humans for a purpose and that is the attainment
of their own perfection in the service of God.
As for God's intimate interaction with His creation and His knowledge of everything
they do in Islam, the Qur'an says:
And certainly We created man, and We know what his mind suggests to him, and We are
nearer to him than his life-vein. (50:16)
...and He is with you wherever you are; and Allah sees what you do. (57:4)
Do you not see that Allah knows whatever is in the heavens and whatever is in the
earth? Nowhere is there a secret counsel between three persons but He is the fourth
of them, nor (between) five but He is the sixth of them, nor less than that nor more
but He is with them wheresoever they are; then He will inform them of what they did
on the day of resurrection: surely Allah is Cognizant of all things. (58:7)
And your Lord says: Call upon Me, I will answer you; surely those who are too proud
for My service shall soon enter hell abased. (40:60)
From these verses a few points can be extracted. Firstly, God is ever present and
knowledgeable about all of human action. Secondly, that closeness is extremely
intimate. As the first verse says God is closer to the human than his own life-vein,
which shows that the closeness is not a physical closeness as the life-vein is part
of the human himself. Rather God is aware of even the most intimate thoughts as He
pervades all. Thirdly, He answers the calls (supplication) of his servants.
There are three reasons as to why people who believe in this conception of God
worship Him. The first group worships out of fear of punishment. After all God has
made the human responsible for his actions and the God of Islam while being
Forgiving and Merciful is also Just. Since the human doesn’t know for certain
whether God will forgive him or punish him, this group worships Him out of fear of
their actions so that He will forgive them. Their fear may also be of trial and
tribulation and so they worship God to save them from that.
The second group worship God in hope of attaining His reward. God has promised great
reward of eternal bliss for those that choose the correct path and so this group
makes that reward their purpose in worshipping.
The last group worships God because He is worthy of worship. When God affects the
mind of His servant, he is overcome with love and awe. God in his eyes becomes
greater than anything and he lives his days in doing good deeds, gaining more
knowledge about God and worshiping Him. While the people in this group may fear
punishment and desire reward that is not the purpose of their worship. This is the
worship of the free.
May you always be successful. May God open your mind more and may He make you a
cause to open the mind of your friend.
'Abd Allah Esmail