Jehovah's Witnesses believe that all the churches of Christendom are false and dominated by Satan. They believe they are the only true Christian religion in the world today. Their literature says that only JW's have any scriptural hope of being saved. Watchtower Sept 1, 1989
But what if it's the other way around? What if all the churches of Christendom have 'the truth' and JW's do not? It's important for JW's to 'make sure of all things' by examining unbiased facts outside their organization. Why? Because if armageddon is right around the corner like JW's believe, what if their religion is the one slated for destruction by Jehovah?
Why would Jehovah destroy a religion that carries his name? Perhaps he is angered that the organization claims to be his channel of communication. Maybe they are not. Maybe they just think they are. Or perhaps he is angered that prophecies have been made in his name that didn't come true. Or perhaps Jehovah is upset with the way JW's treat 'apostates'. Jehovah is a God of righteousness and judgment. It doesn't take much to anger him.
Since they have spoken on behalf of Jehovah, it makes sense that their god will hold them to a higher standard than all other religions. Individual JW's need to be sure they're not sitting on the wrong side of the fence when armageddon strikes.
A Christian's salvation depends upon being a follower of Jesus. Matthew 7:21-23 The Bible says that ALL authority in heaven and earth has been given unto Jesus, - not Moses, the Apostle Paul, the early Christian congregation, or even a modern day religion, ... The Bible says that Jesus has words of eternal life. That's a Bible based fact according to Jude 1:21; John 3:36; John 6:68; Matthew 28:18