"By this all men will know that you are my disciples, if you love one another."-John 13:35 The most important identifying factors for "true" religion hinge on how persons follow these commands. Individual "imperfection" is irrelevant. Choice in doctrines is secondary, to be considered only after first determining whether the religion follows the law of love.
While love is a identifying mark, I would think that TRUTH itself is also a mark. Love itself proves nothing, as there are plenty of non-Christian religions that teach the concept of "perfect" love. As the Lord said in John 17:17 "Sanctify them through thy truth: thy word is truth." So Truth sanctifies us, it determines who we are and what we are. So knowledge of the Truth is important. ALthough not the perverted knowledge that the JW are fed, as their Truth is not stagnant, it's ever changing and how can one ever learn about God and Christ, if they keep changing what God and Christ said and meant?
RR