As believers we do not believe in someone dying and then returning back to this earth in another form. We are all given one life and one opportunity in this life we find ourselves, and it is wise that we make the most of it while we have the opportunity to do so.
Hebrews 9:27 - And as it is appointed unto men once to die, but after this the judgment
This is just how God designed it. What comes after death is judgement and not another life. We ought to live our lives with this awareness. It is good for us to know the truth and not be deceived by doctrines that are not true.
Not everything we should take in and believe to be true. Before we agree to any doctrine we must first of all find out and make sure that it corresponds to what God is saying concerning that matter.