Allah, the Almighty, is ideal. He is the 'Just' and the Judge, as well as the 'Avenger of Evil.' It follows that to test mankind one must judge fairly and punish those who do evil. An example of Allah's justness is that we are only accountable for our own actions, unlike the Christian concept of the original sin, for the Quran says that no bearer can bear a burden of another.
Muslims do not agree with the Judaeo- Christian concept of God having the necessity to rest as they say he did after creating the world. All god needs to say is 'Be and it is.' Tiredness is a human attribute as is making mistakes, this is not applicable to god who is infallible. Allah is also pre-existent to all he has created, he is the first, and as Aristotle put it in his cosmological theory 'the prime mover.'
Allah, the Creator has perfect knowledge. Muslims believe in the omniscience of Allah, He knows all that is tangible and that is manifest, He knows the past and the future. Muslims rebuke the Christian belief that god does not have perfect knowledge, for example in the bible it says that God underestimated the intelligence of His creations- He did not think that man could build the tower of Babel (Genesis Ch11 v5-7, Exodus Ch32 v14). Muslims argue that having created everything, He knows all that there is to know.
To be a Muslim it is essential to believe in the destiny, whether good or bad, that Allah has set for us (known as Qadr in Arabic). The Quran says:
"Say, Nothing shall befall us save that which Allah has ordained for us"
This however does not mean that man does not have free will, for if he did not Allah's justice would be compromised for you cannot judge a person if he does not have the freedom of choosing what he does. Allah, the 'Just', has given man both destiny and free will, the action of a human is interrelated with destiny and both are mutually necessary, as Imam Ali son of Abi Talib (AS) said:
"The predestined will of Allah and the action of a human are like the spirit and the body, the spirit without the body has no physicality and the body without the soul is a picture without movement. If the two are adjoined they become like Al-Qadr and action, for if there was no Qadr then you would not know the difference between creation and creator, and if there was action without it being willed and predestined by Allah than it would not happen."
Some things such as our deaths and disease are above human will, no matter what a person does, if for instance God has set the hour at which you are to die than it will be so:
"And no soul can die except by Allah's leave- a decree with a fixed term" Holy Quran 3:146
"They say 'If we had any part in the government of affairs, we should not have been killed here.' Say 'If you had remained in your homes, surely those on whom fighting had been enjoyed would have gone forth to their deathbeds." Holy Quran 3:155