There are many benefits to this method. 

• It very quickly either bridges to the gospel or determines what someone believes, especially if one asks, "Why do you believe that" after most answers.
• It keeps the person in their world. In other words, you're not preaching at them, but asking them about their beliefs.  Doing so keeps the conversation from being confrontational.
• Almost always, it avoids two objections that can easily become confrontational and may result in the responder not seeing truth.

• Is being good enough, good enough to get into heaven.  Most unbelievers believe that a good God will give them entrance if they really try to be a good enough person.  They believe this strong enough that any challenge to this belief normally brings up resistance. Once they agree that in their world, heaven is perfect and they aren't, and they don't know how the transformation happens, the confusion is theirs.  You haven't presented anything to them, only followed up their answers with other questions.  Very few people who think good enough gets them to heaven have even thought of how they get perfected when they die.

• The validity of the Bible.  Questions about this is a much used objection to believing in the God of the Bible.  When most unbelievers are asked why they believe what they believe, their lack of foundation is clear to them and in any event doesn't compare to the Bible.  The exception is when talking to a cult member.  They use and say they value the Bible but they use either other books (Mormons) or their leaders (Jehovah Witnesses) to interpret the Bible through.  An approach with them is to ask them how they are sure those who wrote the books or their leadership are correct when in conflict with an overwhelming number of Christian translators.