Why did Allah give magic the power of effect?

Dear Brother / Sister,

Allah gave man the freedom to act based on his freewill. Man wants and Allah creates. For instance, if fire did not burn a believer but burnt an unbeliever, or if roses fell down from the sky on the heads of the people who performed prayers and stones on those who did not, everybody would embrace Islam and there would be no difference between Abu Bakr and Abu Jahl.  

Allah treats those who obey and do not obey the rules He imposed in the universe equally so that the test will go on.

Allah allows those who use magic due to this reason and similar ones.

Questions on Islam