Some choice counsel from Thomas Chalmers to a Christian lady struggling with doubts (1826). His distinction between having a concern about what and not how to believe is especially choice.
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But, generally, you complain that you are ignorant of how to go—how to believe. Now this has long been a stumbling-block to many; their thoughts are how they are to believe, when their thoughts should be what they should believe. They look inwardly for the work of faith, when they should look outwardly for the object of faith. “For every one thought,” says Richard Baxter, “that he casts downwardly upon himself, he should cast ten upwardly and outwardly upon Jesus, and upon the glorious truths of the Gospel.” You say that you have no doubts of the freeness of Christ’s salvation, and of His willingness to save you. Dwell upon this; persist in this ; stand in the Gospel attitude of looking upon Jesus, and light will at length arise within you. In the act of looking, you may have to wait a longer or a shorter time for your coming enlargement; but surely it is worth the waiting for. Meanwhile your business is prayer; a diligent attention in the ordinances of religion; reading of God’s word; and, above all, a keeping of the sayings of Christ: ” He that keepeth my sayings, to him will I manifest myself.” Be assured you are in good hands, even in the hands of Him who will not break the bruised reed nor quench the smoking flax.