What is the main conflict in The Cross and the Switchblade by David Wilkerson?

This book chronicles the spiritual journey undertaken by the young evangelical pastor of a small-town, American church when he embarks on a mission to help the members of troubled street gangs in New York City. Set in the late 1950's and early 1960's, the narrative traces the growth of his ministry from personal, one-on-one encounters into a thriving, sometimes miraculously funded, community outreach program. Along the way, the book explores themes relating to the power of Christian faith and the causes and effects of drug addiction.