Why does Les love to tie the Old and New Testaments together?
The driving reason is that the Old and New Testaments fit together intrinsically. Paul's letters aim to teach not only simple things but how all Scriptures tie themselves together, making this connection the whole purpose of his letters, so he values showing their unity.
Les explains that Paul's whole purpose in his letters is to teach us not just some of the simple things, but even how all of these Scriptures tie themselves together. That is why he loves to tie the Old and New Testaments together: they fit so intrinsically. In I Corinthians chapter 10, Paul goes way back to the book of Exodus. He says, "Moreover, brethren, I would not have you be ignorant, how that our fathers were under the cloud, and they all passed through the sea," that is the Red Sea and its parting. Then verse 2 says they were all baptized unto Moses in the cloud and in the sea. Les points out that most people think of water when they see the word baptized, but even though the Red Sea water was parted, the people did not get wet; they walked through on dry ground. The baptism here is connected to the called-out assembly, the Ecclesia, called the Church in the wilderness, but Israel was not baptized to become members of that Ecclesia. Les then refers to Acts chapter 7, where Stephen preaches to his Jewish religious leaders, traces Jewish history back to Abraham, and in about verse 36 refers to their forefathers who came out of Egypt under Moses.