The following is from the book "The Theology of the Cross" by Daniel M. Deutschlander:
What is the litmus test of genuine Christianity today? The old tests can never be completely put away; attacks on the person and work of Christ, attacks on the purpose and nature of the church, attacks on the source and authority of the Bible are renewed in every age. And yet each age has its own special litmus test in addition to these universal and ever resurfacing ones. What might a special litmus test for our day be? Could it be the theology of the cross that separates genuine Christianity from corrupted and counterfeit versions of the same?
We see on every hand a desire to make Christianity fun and happy-go-lucky. Some churches and their leaders go so far as to claim that God really wants Christians always to be healthy, wealthy, and wise. Others turn worship services into hours of self-discovery; the goal is to give the Christian personal fulfillment and better character. If the individual can learn to get along better with himself, then he will get along better with everyone else too, and God should be happy about that. Still others are obsessed with the notion that the true church should be successful, big, and influential in world and national politics. Within the church, no matter what denominational label the particular church may wear, many members want to be their own bible; they want the freedom to pick and choose what doctrines to believe and what behavior to praise or blame. Their choices change with their circumstances of the moment, and woe betide any preacher who tells them on the basis of the Scriptures that they are wrong and their choices damnable in the eyes of God. All of that is a theology of glory, a theology which lets man be his own god and turns the God of the Bible into a creature subject to personal whims of the moment.
The God of the Bible—the one, true, and only God, however, is the God of the cross. Jesus calls us to submission under his cross and then to bear the cross that he sends us and by which he marks us as his own. He did not come to entertain but to redeem us by his blood. He does not call us to be our own gods but to bend low before his cross in total submission to his Word and then to the cross that he is pleased to send. The cross of his own sending always and of necessity and by definition means struggle for us. The cross is not merely a piece of jewelry worn around the neck but pain carried on the heart and in the soul. Jesus calls us to the cross and sends one after another for us to bear. He bids us imitate him in stumbling under its sometimes crushing weight and to cry out in anguish as he did in the midst of its pain. All of that seems so, well, so un-American. We pursue pleasure, and for every pain there should be an instant remedy. We are addicted to entertainment and want church to be entertaining too. We shun any notion that we live in a veil of tears, in einem rechten Jammerthal, as our forefathers put it. We think that anyone who is in physical or spiritual pain must be sick and in need of therapy that will make him happy again—and soon!
At the same time, the Bible tells us that in the midst of suffering and under the cross, we should rejoice. Yes, it tells us to rejoice constantly and precisely because we are suffering under the weight of the cross that crushes and threatens to destroy us. It assures us again and again that those who rejoice without the cross and those who suffer without joy understand neither true joy nor the value of the cross that God has sent.
So we come again to the question: Could the theology of the cross be the litmus test of genuine Christianity in our day? The corrupt and the counterfeit push aside the whole concept of cross bearing in favor of a joy without it. Fake Christianity offers the Christian an imitation of Christ’s glory in heaven, not of his humiliation on earth. The phony and the artificial church turns worship into a spiritual happy hour devoid of repentance, with cheap absolution, with no thought of taking God seriously in either the law or the gospel. And people love it. They still get to be their own god, their own bible, their own source of ultimate truth and salvation.