participating in inter-faith dialog does not mean you are converting or saying "every religion is right". it's the sharing of one's faith with others and respecting others for their choices, whether we feel they are right or wrong.
A muslim cannot respect a Christian for his beliefs that (i seek refuge in Allah from writing this) "God has begotten a son" and any one who does that is a christian and not a muslim.
A muslim cannot respect a Hindu for worshipping lingam
(i.e. penis) and other sexual organs and idols and if any muslim does that he/she is not a muslim.
And similarly for other religions.
By respecting a non-believer a person is acting trechrously to non-muslims because a muslim he knows they will eternally goto hell and even then he/she doesnot try to save them from hell.
What will these inter-faith dialogs achieve at the end may be clear from following Hadith.
Sunan Abu-Dawud Book 35, Number 4230:
Narrated Abdullah ibn Umar: When we were sitting with the Apostle of Allah (peace_be_upon_him), he talked about periods of trial (fitnahs), mentioning many of them. When he mentioned the one when people should stay in their houses, some asked him: Apostle of Allah, what is the trial (fitnah) of staying at home? He replied: It will be flight and plunder. Then will come a test which is pleasant. Its murkiness is due to the fact that it is produced by a man from the people of my house, who will assert that he belongs to me, whereas he does not, for my friends are only the God?fearing. Then the people will unite under a man who will be like a hip?bone on a rib. Then there will be the little black trial which will leave none of this community without giving him a slap, and when people say that it is finished, it will be extended. During it a man will be a believer in the morning and an infidel in the evening, so that the people will be in two camps: the camp of faith which will contain no hypocrisy, and the camp of hypocrisy which will contain no faith. When that happens, expect the Antichrist (Dajjal) that day or the next.