I believe they are a group of writings presenting the beliefs of individuals who essentially started a new religion spearheaded by Paul. However it appears that there were conflicts between early believers regarding Jesus and his role. Especially between Paul and James, hence the reason for division in christian sects today. Christianity as a result does not resemble the simple faith of Abraham (Peace and blessings be upon him).
Nowadays they are discovering many things that show that first century believers varied in their beliefs; Christianity was not one monolithic faith as many believe. In fact different regions had different writings they considered to be inspired. The NT as it exists today was organized by bishops in the 4th century who had grave errors in their theology and selected the writings that best suited them. As a result many were beaten or killed for possessing any other writing.
Of that is just a brief statement of how I feel about the NT. All of this cast a great deal of doubt as to the validity of christianity as a belief system.