It’s easy—even natural—to be a hypocrite. People are enamored with outward appearances, and it’s not difficult to construct a convincing façade. At some point, most people realize there’s no need to develop character and establish integrity when it’s far easier to fake it.
Spiritual hypocrisy is easier still. Few people—and few religions, for that matter—take sin seriously. What you say you believe doesn’t necessarily dictate how you live. In fact, society would prefer if it didn’t.
That’s what makes the believer’s integrity so offensive to nonbelievers, and why they love to uncover hypocrisy in the church. It proves that, regardless of what Christians say they believe, they’re no better than the unsaved world.
The tragedy of such hypocrisy is not that it merely contradicts your faith claims. As a Christian, hypocrisy betrays your new identity and nature in Christ, which is the source of your ability to have integrity in the first place.
In his book The Power of Integrity, John MacArthur explains the fundamental transformation that takes place when a sinner is redeemed.
When you were brought into God’s kingdom, you were totally transformed. You became “a new creature; the old things passed away; behold, new things have come” (2 Corinthians 5:17). You didn’t just receive something new—you became someone new. Paul said, “I have been crucified with Christ, and it is no longer I who live, but Christ lives in me; and the life which I now live in the flesh I live by faith in the Son of God, who loved me, and delivered Himself up for me” (Galatians 2:20).
The new nature is not added to the old nature but replaces it—an exchange occurs. The transformed person is completely new. In contrast to the former love of evil, the new self—the deepest, truest part of a Christian—now loves the law of God, longs to fulfill its righteous demands, hates sin, and longs for deliverance from the unredeemed flesh—where sin still resides. Sin no longer controls you as it once did, but it still entices you to obey it instead of the Lord.  John MacArthur, The Power of Integrity (Wheaton, IL: Crossway, 1997), 18-19.
The apostle Paul had that transforming work in mind when he wrote his letter to the Ephesian church. In fact, he charges his readers to live consistent with the transformation the Lord has already accomplished.
That, in reference to your former manner of life, you lay aside the old self, which is being corrupted in accordance with the lusts of deceit, and that you be renewed in the spirit of your mind, and put on the new self, which in the likeness of God has been created in righteousness and holiness of the truth. (Ephesians 4:22-24)
He makes the same exhortation to the Philippian church, encouraging them to “work out your salvation.” It’s not a command to create or manufacture the new nature in Christ, but to manifest God’s inner transforming work through your outward life.
That new nature permeates your entire life, informing your thoughts, actions, and attitudes. It gives you freedom from the bondage of sin and recalibrates your heart according to God’s law and His righteousness. In fact, it’s what gives you the ability to have integrity before the Lord and the watching world in the first place.
To compromise this new self—this new creation—is the greatest injustice we can do to God. He saved us, transformed us, gave us a new nature, and renewed our minds. Thus the capacity to live a life of integrity is inherent in our new nature. You must grasp this fundamental element of your salvation before you can ever hope to build a life without compromise.  The Power of Integrity, 18-19.
The result is that the believer lives in a state of constant war with himself. The temptation of sin and the ease of compromise will always be present, tugging at his flesh. Combatting those old inclinations is the new nature the Lord has created within. And the longer the believer gains victory over his former sin through his new nature in Christ, the more he builds a track record of integrity.
However, as most mature believers will tell you, the energetic passion of your newly converted soul can fade over time. Your ears don’t stay as closely tuned to the teaching of God’s Word, your heart hardens to the work of the Spirit, and your affections cool to the righteousness God demands. As John MacArthur explains, that is when you’re most susceptible to compromise.
If you are not careful to preserve and protect the treasure that is your relationship with Christ, the exuberance and devotion of your first days with Jesus can slowly and subtly turn into complacency and indifference. Eventually cold orthodoxy replaces loving obedience, and the result is a hypocritical life that will compromise with sin.  The Power of Integrity, 18.
We’ll deal with the strands of hypocrisy that Christians frequently fall into next time.
For now, consider this glorious truth: That in the Lord, we’ve been released from the bondage of sin, redeemed from the wrath we had earned, and restored to a right relationship with the Lord. Instead of being controlled by our flesh, we have the Spirit living and working within us to break the habits of our former lives and grow us in godliness.
Living with integrity simply means living out those rich realities.