In the fifteenth episode of "Nurturing Spiritual Growth," Duane discusses how believers can progress from spiritual infancy to mature discipleship in Christ. He highlights the importance of consistently engaging in four foundational spiritual activities, which he compares to essential food groups in a balanced spiritual diet. These activities are based on Acts 2:42 and include the apostles’ doctrine, fellowship, breaking of bread, and prayer. 

The significance of the apostles' doctrine provides the theological framework necessary for understanding and living out New Testament truths. This doctrine is vital for believers to accurately interpret and apply biblical principles in their lives. Christians risk falling prey to misconceptions and false teachings without a solid grasp of apostolic teachings.

Fellowship is the second component, and it is crucial for spiritual growth. Duane compares spiritual growth to natural maturity, explaining how just as marriage and family life can accelerate personal maturity in the natural realm, spiritual fellowship—consistent, deep interaction with other believers—facilitates spiritual growth. He suggests that isolation can hinder one's spiritual development and expose one to the risks of falling into error or heresy. Fellowship provides the support, accountability, and encouragement needed to navigate the complexities of life and faith.

The third component, the breaking of bread, encompasses both communion and shared meals among believers. Sharing meals fosters intimacy and community among Christians, echoing the practices of the early church. This act of communion is not only a remembrance of Christ’s sacrifice but also a celebration of the unity and mutual care within the body of Christ.

The fourth and final component is prayer. Various types of prayers are available for different circumstances and needs. Effective prayer life is taught and learned within the community of faith and is essential for personal communion with God and corporate spiritual warfare.

In order to grow, believers should balance these practices and consistently engage in them. They should apply these principles and live them out, promoting both personal and communal spiritual development.