The great contrast to this evil course is provided in the supreme example of Christ.  We perceive the love of God towards us, in that Christ laid down His life for us.  I note here that the words of God have been supplied by the translators.  They could just as easily have added of Christ, since it is clear that it is the Lord Jesus of Whom he speaks.  Nevertheless, it is entirely proper to speak even of the humanity of Jesus under the titles of deity.  Paul did this while speaking to the Ephesian elders in Acts 20:28, when he spoke of God purchasing the church with His own blood.  So, I can find no fault with the helpful interpolation the translators added here.

That little point aside, the thing that John is driving at is that we are to be imitators of the noble example of Christ.  Never was there a more splendid instance of self-sacrificing love than when Christ yielded up His body to the cross, giving Himself as an offering and a sacrifice to God, that our sins may be forgiven.  We can never offer ourselves for another’s sin, and need not to do so, for by one offering Christ hath perfected forever them that are sanctified.  But still, as we purify ourselves even as Christ was pure, we can lay down our lives for the brethren.  We can come to their aid, even when they summon us at inconvenient hours, or when it will cost us that vacation money we had been saving up.  We can expend our resources on supporting the work of God in the world, rather than on personal entertainments.  There are innumerable ways by which we can lay down our lives for the brethren, and doubtless we will find more than we are competent to do, if only we look for opportunities, and if we are diligent to follow the pattern laid down by our Master.