Firstly, there is no place where people are not aware, and if it is the case that people are unaware of us, then present our Movement to them. If they accept it then you can pray behind them. Otherwise not at all; pray alone. At this time, God Almighty wishes to prepare a Community. To then deliberately mix with those people who He wants to distinguish us from is against the purpose of God.(Fatawa Hadrat Masih Mau‘ud, p. 27)
If they hypocritically do this, as some people have the habit of being Muslim with Muslims and Hindu with Hindus. They should proclaim(Fatawa Hadrat Masih Mau‘ud, p. 25)
that,“We neither consider him as a liar nor a disbeliever, rather, we consider him as a righteous and saintly person, and we consider those who say that he is a disbeliever to be disbelievers themselves because they declare a believer to be a disbeliever.” Thus, we would know that they are truthful. Otherwise, how can we trust them and how can we issue an order to pray behind them? “Disregarding respect for ranks amounts to heresy.” One should be soft when it is appropriate to be soft and harsh when it is appropriate to be harsh.
The Promised Messiah as wrote:
God Almighty has informed me that you are forbidden and absolutely forbidden to offer your prayers behind an imam who pronounced me a disbeliever or liar, or who is in doubt. Indeed, your imam should be one of(Tadhkirah, p. 498)
yourselves. There is an indication of this in one aspect of the hadith of Sahih al-Bukhari: (He will be your imam and will be from among yourselves;)
Hadrat Musleh Mau‘ud ra was asked about observing prayer behind Ahmadis who have not done