Men talk bravely of believing whilst whole and sound; few know it. Christ is the mystery of the Scripture; grace the mystery of Christ. Believing is the most wonderful thing in the world. Put any thing of your own to it, and you spoil it. Christ will not so much as look at it for believing. When you believe and come to Christ, you must leave behind you your own righteousness, and bring nothing but your sin: (Oh, that is hard!) leave behind all your holiness, sanctification, duties, humblings, and so on; and bring nothing but your wants [lacks] and your miseries, or else Christ is not fit for you, nor you for Christ. Christ will be a pure Redeemer and Mediator, and you must be an undone sinner, or Christ and you will never agree. It is the hardest thing in the world to take Christ alone for righteousness; that is to acknowledge Him Christ. Join anything to Him of your own, and you un-Christ Him. Thomas Willcox
It is easy enough to believe the basic historical facts about Christ, but it was also quite easy for people to believe in Christ when He performed miracles before them. When things are going well and men are healthy, they will speak easily of believing as long as there is no cost involved. When things are going well and no one is persecuting you or mocking you for your faith, it is easy enough to believe. But when your belief in Christ begins to cost you something, whether it is the esteem of others or of repenting of sin, things begin to change. When belief in Christ might make you look like a fool, whether in the eyes of the intellectuals or of those who you fear will laugh at you for what you will not do, it begins to take a toll on what you believe. When people find believing easy, they don’t know whether they really believe in truth.
A true faith in Christ is far different than a simple believing the historical things about Him. The devils and those in hell believe in the historical things about Him, but assuredly it makes no difference (for the good) in their situation. While Christ was on earth the demons believed who He was and what He could do, but instead of that being of comfort to them it made them tremble and cry out to Him. The same is true when it comes to the Gospel. It is easy to believe the facts of the Gospel, but it begins to be harder to believe when a person’s sin begins to be opened to his or her eyes. They being to wonder if they really believe because, they think, how can such a sinful person believe? Here is a very fine point (fine in the sense of the fine point of a needle). The Holy Spirit is the only One who can truly convict a person of sin deep in their person. When that happens, people will go one of two ways. They will struggle with the truth of their sinfulness of they will flee from a sight of their own sinfulness.
When a person flees from a sight of his or her own sinfulness, that person will be turned over to more and more sin because the person is hiding from the sight of sin and that is a blinding work and a fleeing from the Gospel of the righteousness of Christ. On the other side of things, however, some will struggle for faith and cry out for belief in Christ and His perfect righteousness in the midst of their struggles of whether they believe or not. They will be astonished at their own sin and their capacity and capability for sin, yet they will hang on to their small belief and pray for more. “I do believe; help my unbelief” (Mark 9:24). This is the heart of all who truly believe (most likely) when the Lord is pleased to open their hearts to see the depths of their sin. They see the sin and unbelief in their hearts and don’t see the little flame of life that is their souls. The Lord, in His great mercy and kindness, teaches sinners Himself in ways that they cannot do themselves and no other can do. He teaches them and shows them how absolutely and utterly they are undone in themselves.
Until Christ the Prophet of His people teaches the soul and brings it through the fire of trials and temptations, the soul will no truly know itself and as such will think that it has great faith when it has but little or none at all. Those who suppress His teaching about sin will slide into more actual sin while suppressing the knowledge of that as well, but those who seek the Lord for a greater knowledge of themselves will see more sin but they will also begin to see more of the glory of the Gospel of free-grace and a perfect righteousness that comes to sinners by that free-grace. For a soul to earnestly and truly believe in Christ, that soul must leave behind all of its own righteousness, duties, and even all of its sanctification. After all, Christ is the sanctification of all true believers. When a poor sinner who is distraught at the sight of his own sinful and evil heart comes to Christ, that sinner will not bring anything of his own righteousness to Christ because that sinner knows that s/he has none to bring. That sinner knows that it is free-grace alone that can save him or her from sin and that s/he has no sanctification. That sinner wants nothing but Christ alone and wants Him by grace alone because s/he knows there is no other way.