It is a genuine question and one professing believers should sincerely be interested in, considering his popularity among Christiandom. We are indeed to judge a man’s fruit, doctrine and testimony (e.g., Mt 7:15-20; Rom 16:17-18; 3 Jn 1:9-11; Ju 1:3-16; 2 Pet 2:1-22; entire Epistle of 1 John; etc). The Biblical test will either (majority of the time) conclusively point to genuine conversion and thus a true fruitful Christian life, or feigned testimony and false Christian life