Every new Christian and a whole lot of old ones need someone to lead them through the essentials of following Jesus right now.  The reality is that everyone should have someone(s) leading them to follow Jesus (become like Jesus) for life, and every follower of Jesus should be leading 1-3 other people to follow Jesus.  However, there is a specific and vital necessity to invest in new believers immediately to ensure they are equipped with the knowledge and practices to thrive in relationship with God.