The Altera Civitas: A Community of Authenticity

In his book An Introduction to Ecclesiology: Ecumenical, Historical & Global Perspectives, Veli-Matti Kärkkäinen refers to the church as the altera civitas—the “other city.” This concept portrays the church as an alternative community, one that challenges prevailing assumptions about life and belief.

The Standard of Authenticity

For the church to be this unique city—the altera civitas—there must be a standard by which it is measured. That standard is nothing less than the Triune God. Because God is Community—specifically, Community on mission—the defining qualities that make the altera civitas distinct are found in Him.

Among these qualities, or core values, three stand out: authenticity, accountability, and availability. Let us focus on the first: authenticity—being real.

To embrace authenticity is to lay claim to undisputed credibility. At the heart of authenticity is genuineness, even integrity. To say someone or something is authentic is to affirm its utter truthfulness. These are precisely the attributes of the Triune God.

Consider Isaiah 65:16, where God is twice called “the God of truth.” Or Romans 15:8, which speaks of Jesus becoming a servant “to show God’s truthfulness, in order to confirm the promises given to the patriarchs.” Likewise, 1 John 5:6 declares, “The Spirit is the truth.” These passages reveal each Person of the Trinity as wholly and unquestionably true. God is authentic.

An Obligation to Truth

Because God is true, the church is obligated to reflect that same truthfulness—to be true to God, to itself, and to the world in which it resides. Only by such commitment can the church truly function as the altera civitas—humbly yet courageously confronting the prevailing beliefs and values of its time. This radical commitment to truth is what distinguishes the church from a world that often proclaims there are no absolutes.

Authenticity, modeled after God’s own nature, is the starting point for this commitment. One practical expression of this is for the church to harmonize its existence in a broken and sinful world with its identity in the person and work of Jesus Christ—once crucified, now risen. Because Jesus is true—genuine—the church is invited, even compelled, to be real as well.

This is exemplified when the church reaches out to the disenfranchised in its local context. Such service mirrors the intentional compassion of Jesus, who, for example, sought out the man at the Pool of Bethesda to bring healing (John 5:1–17).

Reckoning with Reality

As this kind of authenticity is lived out, those who encounter the altera civitas must reckon with a compelling (and at times unsettling) reality: the God/Man, Jesus Christ, is genuinely on display—through the lives of redeemed rebels. In facing the church, they are, in fact, facing Him.

They may choose to walk on. Or they may choose to enter the city. But because the altera civitas offers a true portrait of the Incarnate God—before whom every knee will one day bow (Philippians 2:10)—a decision must be made.

And it is the authenticity of Jesus' people that both creates this tension and extends the invitation: Come.