if u have some enmity with him then please do keep it with urself. U must know him thoroughly then speak out. Hazrat Maulan Md Kaleem Siddiqui sahab is one of the best Da'ee around the world, and for me he is the BEST. Preaching and converting a non muslim brother is not a game. Its upon Allah subhanaho ta'la. What have u done till now with this fard e ain...?? U neither give dawa nor u accept it...it seems...!! Go through his book ' NASEEM-E-HIDAYAT KE JHONKE' in hindi or urdu and WINDS OF ISLAM in english then only u will know who he is...??
MAY ALLAH GIVE HIDAYAT TO US ALL..AMEEN.