What is the Essential Christian Truth About the Nature of God?

In this blast from the past, J. Warner Wallace examines the classic theological definition of God. What must we, as Christians, agree on related to God's nature? Can we be wrong about the nature of God and still be 'saved'? Can other groups (such as Mormons or Jehovah's Witnesses) have a different view about the nature of God and still call themselves Christians? Are there any good philosophical or evidential reasons to conclude that the Christian view of the "Trinity" is reasonable?