Contents of George Whitefield's sermons: What about laypeople of the Bible and the church?

It is a widely known fact that most of audience of Whitefield's sermons were the laity or even laypeople who do not know about the Bible and the church at all: mine workers, laborers, the poor, and so forth. Since these people were not able to reach out to the church, Whitefield tried to preach for them in the open air. However, terms and the logic Whitefield employed in his sermons seem to be a bit difficult for those people. Not only that, these do not seem to be sympathetic, as well, for laypeople.  For instance, Whitefield said that "if you do not believe this (religion to be an inward thing), though you have got your Bibles in your hand, you hate the Lord Jesus Christ in your heart; for religion is everywhere represented in Scripture as the work of God in the heart" and " Christ's whole personal righteousness is made over to, and accounted theirs. They (we) are enabled to lay hold on Christ by faith, and God the Father blots out their (our) transgressions, as with a thick cloud...they (we) are made the righteousness of God in Christ Jesus."

Some parts of the sermons were not even easy for me to grasp. Therefore, I was wondering whether audiences fully understood his sermons or not, and did contents of his sermons indeed change people? not his physical or external abilities: speech, deliverance or power of persuasion?