Without doubt, Dr. Stephen Wellum has been the most influential professor for me during my time at Southern. I am currently taking my seventh class with him in three semesters. A little over a week ago, I posted about Dr. Wellum's chapter on the relation of the covenants and its implications for baptism being posted on-line for free. It is a long chapter, but if you're too busy, print it out while its free and get to it later. It is an extremely helpful article that will help you understand how the Bible fits together, and how the ordinance of baptism fits into that scheme. Justin Taylor has interviewed Dr. Wellum about his chapter. I highly recommend it.