Question: I want to know about Qadiyani Ahmedia sect, are they really Muslims? Can one pray Janazah (funeral over them or can we take part in their Janazah?
Answer: Muhammed s.a.w is the final messenger of Allah s.w.t which is confirmed in many verses of the Quran and many ahadith of Rasul s.a.w. Until the day of judgement there will be no other prophets arriving. If any one denies or have any doubt in this concept, he will no longer remain Muslim.
Sometimes they call themselves Ahmedi Muslims group (though they call themselves Muslims) in fact are not Muslims due to rejecting the concept of last prophet hood. Their claim is that Mirza Gulam Ahmed Qadiyani (13 February 1835 – 26 May 1908) from Indian sub-continent is also a prophet (which is pure lie and deception) thus, rejecting the concept of last Prophet being Muhammed s.a.w.
In light of this, the whole Muslims around the globe has declared that they are not Muslims rather Kuffar (non-Muslims). Due to this fact no Muslim can attend their Janazah nor one can pray the Janazh over them.
Note: By declaring that they are not Muslim, is basically protecting the Muslims from their deception whilst they call themselves Muslims. Unlike normal kuffar (non-Muslims), they are not deceiving anyone by calling themselves Muslims! Thus, no prejudice against anyone.
References: [1] Surah Al-Ahzab, V:40, [2] Tafseer Ibn Kathir, vol-3, p-697 [3] Bukhari: 3534/Muslim: 2286/7 [4] (a) Ahmed, vol-5 p-136 (b) Ahmed, vol-3, p-267 [5] Sunan At Tirmidhi: 2219 [6] Tabrani (Mu’jam al-awsat) vol-3, p-318