Scholars have defined and categorized the call to ministry in various ways. Jeff Iorg defines calling as a “profound impression from God that establishes parameters for your life.” Iorg explains three types of call experiences as 1) the universal call to Christian service and growth, 2) the general call to ministry leadership, and 3) the specific call to a ministry assignment. H. Richard Niebuhr explains the call to ministry as a complex interaction between “person, community, and God.” He describes four elements of a call to ministry as 1) the call to be a Christian, 2) the secret call as an inner persuasion to take up the work of the ministry, 3) the providential call representing God gifting the minister with the necessary talents and guiding his circumstances, and 4) the ecclesiastical call as “the summons or invitation extended to a man by some community or institution of the Church to engage in the work of the ministry.”
A common definition of the call to ministry includes the dual elements of internal desire and external affirmation. Donald Whitney explains that traditionally the call to ministry has been divided into two parts: the internal call and the external call. Whitney describes the call to ministry as God “planting the desire” for vocational ministry into one’s life (internal call) and persuading brothers and sisters in Christ that the desire is legitimate (external call). John Calvin explains that together the internal and external call represent the “twofold calling” of the ministers of the church. Calvin describes the internal call as the secret call, “the good testimony” of the heart including a “sincere fear of God and desire to edify the Church.” Calvin explains external calling as the formal and public call of the people of God, the “common right and liberty of the Church” when “those who may have seemed fit are elected on the consent and approbation of the people.”
Many contemporary writers reference Charles Bridges in The Christian Ministry for a concise definition:
The external call is a commission received from and recognized by the Church, according to the sacred and primitive order; not indeed qualifying the Minister, but accrediting him, whom God had internally and suitably qualified…The internal call is the voice and power of the Holy Ghost, directing the will and the judgment, and conveying personal qualifications. Both calls, however—though essentially distinct in their character and source—are indispensable for the exercise of our commission.”
Bridges explains the internal call as the Holy Spirit working powerfully in the minister to direct the will and endow necessary qualifications. Internal calling represents God’s Spirit speaking to the heart and inner being of those he has called to serve as ministers. Bridges describes the external call as an accreditation and commission of the church after recognizing God’s work in the minister’s internal calling. In external calling, the congregation evaluates and affirms the character and gifts of the believer who senses God’s leading toward ministry. Spurgeon spoke of the external call as “needful proof” that the will of the Lord concerning pastors has been made known through the “prayerful judgment of his church.” Mohler, Whitney, and Dumas explain that in external calling God uses the congregation to “call out the called” through evaluation, affirmation, commissioning, and joyous celebration. Brian Croft defines the call to ministry as both the internal call, a God-given desire for ministry combined with a conviction that one is gifted and empowered by God’s Spirit; and the external call, an affirmation from a local church that one possesses the gifts and godly character suitable for a Christian minister. Spurgeon, Bridges, Calvin and others in Christian history agree that both the internal and the external facets of ministry calling are essential to a minster’s identity and development.
 Jeff Iorg, Is God Calling Me? (Nashville, TN: B and H Publishing, 2008), 16.
 Iorg, 17-29.
 H. Richard Niebuhr, The Purpose of the Church and its Ministry (New York, NY: Harper and Brothers, 1956), 66.
 Niebuhr, 64.
 R. Albert Mohler, Donald S. Whitney, and Daniel S. Dumas, The Call to Ministry (Louisville, KY: SBTS Press, 2013), 9.
 Mohler, Whitney, and Dumas, 9.
 John Calvin, Institutes of the Christian Religion. Translated by Henry Beveridge. (Edinburgh: The Calvin Translation Society, 1845), 4.3.11 and 4.3.Sections Summary.
 Calvin, Institutes, 4.3.11.
 Calvin, Institutes, 4.3.11 and 4.3.15.
 Charles Bridges, The Christian Ministry (Edinburgh, UK: The Banner of Truth Trust, 1830), 91-92. Contemporary writers who use Bridges as they explain calling: James M. George, “The Call to Pastoral Ministry.” In Rediscovering Pastoral Ministry, ed. John MacArthur (Dallas, TX: Word Publishing, 1995), 102-115; Dave Harvey, Am I Called? The Summons to Pastoral Ministry (Wheaton: Crossway, 2012), 169; and Brian Croft, Prepare them to Shepherd, 15.
 Charles H. Spurgeon, “Lecture 2: The Call to Ministry” Lectures to My Students (Peabody, MA: Hendrickson Publishers, 2011), 34.
 Mohler, Whitney, and Dumas, 15.
 Brian Croft, Biblical Church Revitalization (Fearn, Scotland: Christian Focus Publications, 2016), 41.
 Croft, Biblical Church Revitalization, 41.