(The most recent previous comment on this sermon can be found here)
A careless preacher fails to think, What will this sound like to everyone? If a text contains an encouragement, we may be tempted to think, I am encouraged; everyone will also be encouraged. That is often not the case. If a sermon is the work of a shepherd, the shepherd must not only walk with the most, he must be careful to consider the stumbling and faltering.
In his sermon, Whitefield noted the great victory assured by God – the first Gospel, even in the midst of the
I will put enmity between you and the woman, and between your offspring and her offspring; he shall bruise your head, and you shall bruise his heel. Genesis 3:15 (ESV)
Here we have a promise of struggle – but it contains the hope of victory: the seed of the Serpent will strive with the Seed of the Woman – but the Serpent will be destroyed. Whitefield notes the struggle, but then he comforts:
But let not this dismay us. For in all this the seed of the woman is more than conqueror and bruises the serpent’s head. Thus the Israelites, the more they were oppressed, the more they increased. Thus it was with the Apostles. Thus it was with their immediate followers, so that Tertullian compares the church in his time to a mowed field: the more frequently it is cut, the more it grows. 8 The blood of the martyrs was always the seed of the church. And I have often sat down with wonder and delight and admired how God has made the very schemes which his enemies contrived, in order to hinder, become the most effectual means to propagate his gospel.
Gatiss, Lee (2012-08-15). The Sermons of George Whitefield (Kindle Locations 998-1003). Good News Publishers. Kindle Edition. So this is great good news – nothing will defeat the progress of God’s work.
He then notes that this struggle will not only exist between the believer and world, but it will exist within the person:
Further, this promise is also fulfilled, not only in the church in general but in every individual believer in particular.
Now, at the time he preached there were without question those who that morning struggled with sin. Some may have heard this promise who took instant solace.
But there were others who when heard that Christ will defeat the Seed of the Serpent turned to their own sin and thought, This promise was not for me – I still sin in my life. In fact, such sin has overtaken me …again! Thus, the promise of victory and the song of encouragement will have the opposite effect upon the poor struggling Christian.
Whitefield, wisely turns to the weak and makes the address:
Many of you that have believed in Christ perhaps may find some particular corruption yet strong, so strong, that you are sometimes ready to cry out with David, ‘I shall fall one day by the hand of Saul’ [1 Samuel 27: 1]. But fear not, the promise in the text ensures the perseverance and victory of believers over sin, Satan, death, and hell. What if indwelling corruption does yet remain and the seed of the serpent bruise your heel, in vexing and disturbing your righteous souls? Fear not, though faint, yet pursue. You shall yet bruise the serpent’s head. Christ hath died for you and yet a little while and he will send death to destroy the very being of sin in you.
Whitefield could have completed the sermon without these five sentences. For most of the people, the sermon as it stood would have been more than sufficient. However, Whitefield thought carefully of those who stood to listen.
This is a point at which preaching and counseling overlap: The best preaching must perform the work of biblical counsel; just as the best counseling must be sermons in miniature. There is a kind of preacher who thinks counseling beneath him. While Whitefield’s primary ministry was to astoundingly large groups who came to hear; he did not considered himself too busy with preaching to fail and slow and gather up the broken hearted.
 There is a “joke” which goes with this: The struggling Christian asks, “What must I do about this sin?” The “wise” preacher answers, “What does the Bible say?” The struggling one answers, “To stop.” The preacher, “Then do it.” The preacher does not understand the Christian, nor does he understand the struggle. If he cannot rightly expound the Word in its strength and comfort to one person, we must wonder at the limitations he will face he thinks to expound it to many.