The rendering of this passage is admittedly difficult, as may be gathered from the diverse views which have been propounded. The order of the words is as given in our translation - "A propitiation [propitiatory, or mercy-seat] through faith in His blood." But the question is whether we are to construe "in His blood" with faith, or whether "in His blood" should not be connected with propitiation, as the means indeed by which propitiation has been made. We have no hesitation whatever in adopting the latter view; for it is very evident from what took place on the day of atonement that the blood sprinkled upon the mercy-seat constituted the propitiation. If this interpretation be correct, faith is the subjective means of appropriating Christ, as set forth by God as the propitiation. In other words, God sets forth Christ as a Mercy-seat, in virtue of His blood (for His blood is the testimony that He, the righteous One, laid His life down under the judgment that lay upon man), and faith receives, or appropriates, Him in the character in which He is set forth. Thus faith (as ever) thinks the thoughts of God. Another consideration justifies the above interpretation. The object God has in setting forth Christ as a propitiation is "to declare His righteousness for the remission of sins that are past, through the forbearance of God," etc. That is, in view of the propitiation to be effected in the blood of Christ, God could righteously, in His forbearance, "pass over" the sins of the saints of old; and now He can, on the same basis, show forth that He is righteous in justifying everyone who believes in Jesus. For having been infinitely glorified in the death of Christ under man's judgment (and it is to this the blood bears witness), He can declare His righteousness in the remission of the sins that are past (the sins of Old Testament believers), and in the justification of everyone who is of the faith of Jesus.
"Temptations" in this passage is more what we generally understand as "trials." It is the same word in verses 13, 14, and this will help us to apprehend its use. God's "temptations" are really tests, as verse 3 shows, where the reason given for rejoicing when we fall into divers temptations is that we know that the trying (or proving) of our faith works out, in the issue, patience or endurance. It is in the same sense that we read of God tempting Abraham - that is, that He tested him by the command to offer up Isaac. But when we come to verse 13 (which again is a contrast with verse 12) James speaks of temptation to sin; and, as he teaches us, with this God cannot have anything to do. There is therefore the widest possible difference between the two temptations. On God's part, if He "tempt" us, it is with the object of proving us, of letting us see what is in our hearts; and thus our blessing is the end in view. On Satan's part, for it is he who acts upon our flesh and seeks to stimulate its lusts, it is that he might destroy our testimony, even if he cannot compass our destruction. As another example of the usage of the word, reference may be made to 1 Cor. 10:13. The character of the "temptation" is not here specified; but it is manifest that the Corinthians were assailed by trials which tested their fidelity. To encourage their hearts the apostle assures them that there was nothing extraordinary in what they were passing through, that it was only what was "common to man." Then he brings in God in the most beautiful way, God in His faithfulness, as the support of their souls, and tells them that He will not suffer them (for He was watching over them) to be tempted above that they were able; but will with the temptation make a way of escape, that they may be able to bear it. Blessed assurance and a blessed stay for the tried and desponding heart. It will then be seen from these and similar scriptures that the temptations in which we are to rejoice are those which, meeting us in the wilderness path, test our confidence in God, and show us in how far we are depending on Him for our strength and support. Peter also speaks of these temptations, and in connection with the trial of our faith in the light of the future - at the appearing of Jesus Christ. (1 Peter 1:6, 7.)