It is forbidden to arrange a discussion or a debate with one who prophesies in the name of idols (or with one who prophesies in the name of G-d to serve idols; both have the same status as a false prophet), and he should not be asked to perform a sign or a miracle. If he makes a sign or a miracle on his own, one must not pay attention to it or think about it. Anyone who thinks about these so-called miracles, debating if they are true, is a sinner, since the false prophet obviously denies a foundational principle upon which everything in Torah depends, as it says,40 "If a prophet or dreamer of a dream shall arise among you, and he will give you a sign or wonder, and the sign or the wonder comes about, of which he spoke to you, saying, 'Let us follow other gods, ... and we shall serve them!' - do not hearken to the words of that prophet or that dreamer of a dream ..."41
40 Deuteronomy 13:2-4.
41 Rambam, Laws of the Worship of Stars (and Idols) 5:7 (the Divine Code by Rabbi Moshe Weiner, Ask Noah International, 2018, p 53).