What is Kufr bit Taghut?
The term comes from Arabic and means: To disbelieve in false god. It is what all the Messengers of Islam came with to warn their people about.
It involves rejecting every idol. In the past, there were many false gods that were worshiped. The Messengers came to warn them of that, and to proclaim to worship Allah alone.
And verily, We have sent to every nation a Messenger (proclaiming): “Worship Allah and reject the Taghut (idol).
This concept is an important part of Islam. It rejects polytheism to maintain monotheism. Every Muslim is therefore commanded to observe this concept.
Worshiping another besides Allah is a great injustice in Islam. Whoever does so commits major Shirk, and thereby worships the Taghut.
Kufr bit Taghut is a pillar of the Shahada which bears witness that no one has the right to be worshiped besides Allah. The Islamic creed is invalid if one does not practice Kufr Bit Taghut.
This concept of Islam is paired with Emaanu billah (Believe in Allah), which is the first pillar of Imaan.
Anyone who disbelieves in Taghut and believes in Allah has grasped a strong hold that will never break. And Allah is the All-Hearing, the All-Knowing.