Act 2:12

Act 2:12  And they were all amazed, and were in doubt, saying to one another, What does this mean?

Interpretation:
       All of the people that heard the disciples were is shock and amazement, but at the same time they were full of questions and doubt.  Doubt and questioning are not all the time bad...  God actually tells us to test the spirits and see if it is from Him.  So I think this group had sincere questions about the subject that the disciples spoke about, which was God and the works of God.  They were "seeking" if you would.  
     But doubt and questions can be a bad or unhealthy thing too, if you don't watch it.  Because as a Christian there are certain points were we have to just have childlike faith.  I heard a man say "If you can totally understand or wrap you mind around God, He wouldn't be big enough to worship!"  The Bible also says to stay away from endless discussions and idle talk, basically meaning there are certain things that we can't grasp and if we set and try to we will either come up with some whacked out reason, or we will just short circuit :)
      Ultimately Do you believe in God?  And do you think He is Good?  Then just follow hard after Him and don't worry about the rest... Keep the Main Thing, The MAIN Thing!

Application:
      Practically I am going to do everything I can to surround myself with Godly things, to keep my mind focused on Him.  We were created for Jesus and I want to be consumed with Him, Because He is the MAIN THING!!!