After Jesus’ death and resurrection, stories and memories of him circulated by word of mouth. Jesus’ disciples, including Paul and his companions traveled and founded new communities. The earliest Christian writings we have are letters, especially those of Paul, written 15-30 years after Jesus’ death. These letters advised and encouraged fledgling Church communities when their founders had moved on.  There may have been other writings, including a collection of Jesus’ sayings, that were not preserved. As some disciples died, and fewer people were able to give firsthand accounts of Jesus, writings were needed, and so the Gospels were written.