From BiblePortal Wikipedia

Doubts [1]

And Fears, are terms frequently used to denote the uncertainty of mind we are in respecting our interest in the divine favour. The cause of our doubts may be such as these: personal declension: not knowing the exact time, place, or means of our conversion; improper views of the character and decrees of God; the fluctuation of religious experience as to the enjoyment of God in prayer, hearing, &c.; the depth of our affliction; relapses into sin; the fall of professors; and the hidings of God's face. While some are continually harassed with doubts and fears, there are others who tell us they know not what it is to doubt: yea, who think it a sin to doubt: so prone are men to run to extremes, as if there were no medium between constant full assurance and perpetual doubt. The true Christian, perhaps, steers between the two. He is not always doubting, nor is he always living in the full exercise of faith. It is not unlawful at certain seasons to doubt. "It is a sin, " says one, "for a believer to live so as not to have his evidences clear; but it is no sin for him to be so honest and impartial as to doubt, when in fact his evidences are not clear." Let the humble Christian, however, beware of an extreme. Prayer, conversation with experienced Christians, reading the promises, and consideration of the divine goodness, will have a tendency to remove unnecessary doubts.