What is the definition of Ahmadiyya? And what is their belief?

If by Ahmadis one means those affiliated with Ahmad al-Rifa'i, then their beliefs include polytheism (shirk) and other forms of disbelief (kufr), extremism (ghuluw), and innovations (bid'ah). They also turn away from much of what the Messenger brought, show disdain for the Islamic Sharia, lie, consume people's wealth unlawfully, and hinder people from the path of Allah, despite displaying some outward signs of worship, devotion, and asceticism. However, if the Ahmadiyya Qadiani are meant, their beliefs and tenets have been previously clarified.