We live in a world, as we see in the political realm, where those who disagree are quickly demonized, where partisan concerns are ramped up. As Christians, we mustn’t follow the same path. We need to be vigilant for the truth and to defend the faith. At the same time, we need to be careful about drawing lines too tightly, and to beware of pulling out the heresy charge too quickly.

Paul charges Timothy to “guard the good deposit” (2 Tim. 1:14), which is the gospel of Jesus Christ. We’re to remain vigilant in guarding the gospel because both the Scriptures and also church history remind us that many have swerved from the truth. Even a cursory reading of the New Testament reveals that upholding the truth and the purity of the gospel has been a challenge from the beginning. We aren’t facing anything new in our day, and we have the promise that the church of Jesus Christ will triumph over “the gates of Hades” (Matt. 16:18).

In this article I want to briefly consider threats to the gospel—from the left and from the right.

Dangers from the Left

Paul’s speech to the Ephesian elders is the only speech in Acts addressed to Christians (Acts 20:17–35), and it’s significant that it’s addressed to leaders, to the elders and overseers in the church (Acts 20:17, 28). Paul warns them in the strongest terms about the danger of false teaching:

Be on guard for yourselves and for all the flock of which the Holy Spirit has appointed you as overseers, to shepherd the church of God, which he purchased with his own blood. I know that after my departure savage wolves will come in among you, not sparing the flock. Men will rise up even from your own number and distort the truth to lure the disciples into following them. Therefore be on the alert, remembering that night and day for three years I never stopped warning each one of you with tears. (Acts 20:28–31, CSB)

As evangelicals we need to be alert to the danger of false teaching. Anyone who knows the history of religious universities in the United States knows that the declension from orthodoxy began with doubts about—and then rejection of—Scripture’s truthfulness.

Some might be inclined to question the concern for orthodoxy and doctrinal fidelity that animates many evangelicals. They might complain that such concerns are defensive and negative instead of positive and constructive. But any reading of the New Testament shows that such defensive concerns are fitting and imperative. We see Paul defending the truth ardently against false teachers in the Pastoral Epistles. Peter shares the same concern in his second letter, and 1 John also engages in a polemic against false teachers.

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