The church of God has great need of these examples [Judah and Tamar]. For what would become of us? What hope would be left for us if Peter had not denied Christ and all the apostles had not taken offense at Him, and if Moses, Aaron and David had not fallen? Therefore God wanted to console sinners with these examples and to say: "If you have fallen, return; for the door of mercy is open to you. You who are conscious of no sin, do not be presumptuous; but both of you should trust in my grace and mercy."
Martin Luther, The Works of Martin Luther, Vol. 7. 11
John Bunyan wrote:
Sometimes a man, yea, a man of God, is, as he apprehends, so far off from God, that he can neither help him, nor hear him, and this is a dismal state. "And thou hast removed my soul," said the church, "far off from peace: I forgat prosperity" (Lam 3:17). This is the state sometimes of the godly, and that not only with reference to their being removed by persecutors, from the appointments and gospel-seasons, which are their delight, and the desire of their eyes; but also with reverence to their faith and hope in their God. They think themselves beyond the reach of his mercy. Wherefore in answer to this conceit it is, that the Lord asketh, saying, "Is my hand shortened at all that it cannot redeem?" (Isa 50:2). And again, "Behold, the Lord's hand is not shortened, that it cannot save; neither his ear heavy, that it cannot hear" (Isa 59:1). Wherefore he saith again, "If any of them be driven out unto the outmost parts of heaven, from thence will the Lord thy God gather thee, and from thence will he fetch thee" (Deu 30:4). God has a long arm, and he can reach a great way further than we can conceive he can (Neh 1:9): When we think his mercy is clean gone, and that ourselves are free among the dead, and of the number that he remembereth no more, then he can reach us, and cause that again we stand before him. He could reach Jonah, tho' in the belly of hell (Jonah 2); and reach thee, even then, when thou thinkest thy way is hid from the Lord, and thy judgment passed over from thy God. There is length to admiration, beyond apprehension or belief, in the arm of the strength of the Lord; and this is that which the Apostle intended by this word, Length; namely, To insinuate what a reach there is in the mercy of God, how far it can extend itself. "If I take the wings of the morning," said David, "and dwell in the uttermost parts of the sea; even there shall thy hand lead me, and thy right hand shall hold me" (Psa 139:9,10). I will gather them from the east, and from the west, and from the north, and from the south, saith he: That is, from the utmost corners . . . O the length of the saving arm of God! As yet thou art within the reach thereof; do not thou go about to measure arms with God, as some good men are apt to do: I mean, do not thou conclude, that because thou canst not reach God by thy short stump, therefore he cannot reach thee with his long arm. Look again, "Hast thou an arm like God" (Job 40:9), an arm like his for length and strength? It becomes thee, when thou canst not perceive that God is within the reach of thy arm, then to believe that thou art within the reach of his; for it is long, and none knows how long.
John Bunyan, The Works of John Bunyan, Volume 2, 3/373