What is the repentance for polytheism (shirk) in Allah?

Polytheism (shirk) is the greatest sin. Repentance from it is achieved by uttering the two testimonies of faith (Shahadatayn), returning to the Oneness of God, and dedicating worship solely to Him. Whoever affirms God's Oneness and abandons shirk becomes a Muslim. The Prophet, peace be upon him, said: "Whoever says 'There is no god but Allah' and disbelieves in whatever is worshipped besides Allah, his wealth and blood become inviolable, and his reckoning is with Allah, the Mighty and Exalted." The repentance of an apostate and every disbeliever is by embracing Islam, by testifying that there is no god but Allah and that Muhammad is the Messenger of Allah. As for one who disbelieves by denying an obligatory act, their repentance, in addition to the two testimonies, involves affirming the denied act, or saying: "I disavow every religion that contradicts the religion of Islam."