Without this, healing is impossible

But I come . . . to show that this at present is the state of many professors of religion [professing Christians], that they are fallen under those spiritual decays, and do not enjoy the effects of the promises concerning flourishing and fruitfulness, which we have insisted on. To fasten a conviction on them, or some of them at least, that it is indeed so with them, is my present design; and this ought to be done with some diligence. The glory of Christ, the honour of the Gospel, and the danger of the souls of men do call for it. This is the secret root of all our evil, which will not be removed unless it be digged up. Who sees not, who complains not of the loss of, or decays in, the power of religion in the days in which we live? But few there are who either know or apply themselves, or direct others, to the proper remedy of this evil. Besides, it is almost as difficult to convince men of spiritual decays as it is to recover them from them; but without this, healing is impossible. If men know not their sickness, they will not seek for a cure. Some, when they see their sickness and their wound, will apply themselves to wrong, useless remedies, like them in the prophet Hosea (5:13). None will make use of any cure who see no disease at all. Therefore, to fasten a conviction of this on the minds of some, we may make use of the ensuing inquiries and observations . . . (John Owen, The Glory of Christ. p 263) [emphases mine]

What a needed call in our day:

1. To be convicted of spiritual decay
   
2. To apply ourselves, and direct others, to the proper remedy of this evil

for the glory of Christ, the honour of the Gospel, and the danger of our souls.