To whomsoever among you who wills to walk straight. And you cannot will unless (it be) that Allâh wills the Lord of the ' Alamîn (mankind, jinn and all that exists).
Fourth: To believe that Allah is the sole Creator. He (Exalted be He) created every being with a soul, attributes, and actions. All beings are created by Allah and everything occurs by His will.
Say (O Muhammad ﺻﻠﻰ ﺍﷲ ﻋﻠﻴﻪ ﻭﺳﻠﻢ): "He is Allâh, (the) One. "AllâhusSamad (ﺍﻟﺴﻴﺪ ﺍﻟﺬﻱ ﻳﺼﻤﺪ ﺇﻟﻴﻪ ﻓﻲ ﺍﻟﺤﺎﺟﺎﺕ) [Allâh the SelfSufficient Master, Whom all creatures need, (He neither eats nor drinks)]. "He begets not, nor was He begotten. "And there is none coequal or comparable unto Him."
These are the four levels of the Divine Decree. Whoever believes and understands them, believes in Divine Decree, and its good and bad consequences.
Scholars have mentioned these four levels in `Aqidah books and have clarified its proofs. Among those who explained this issue in brief is Shaykh AlIslam Ibn Taymiyyah (may Allah be merciful with him) in his book, "Al`Aqidah AlWasateyah". However, his student Abu `Abdullah Ibn AlQayyim explained this matter in full in his book entitled, "Shifa' Al`Alil fi Masa'il AlQada' wa AlQadar wa Al Hikmah wa AlTa`lil". This is a very precious, unique, and useful book we recommend you to read.
May Allah (Glorified be He) guide us all to holdfast and understand his religion deeply. We ask Him to guide all Muslims to His Straight Path. He is the Most Generous! Assalamu `alaykum warahmatullah wabarakatuh!