Glad you asked about the “Angelic Conflict”. This is a teaching embraced by and taught most thoroughly by Donald Grey Barnhouse in his book,
“The Invisible War” and a compliment to this study is a work by Merrill Unger,
“Biblical Demonology”.
Donald Grey Barnhouse was a renowned theologian whose work is still received and edifying believers today. Barnhouse started the Evangelical Foundation in 1949 which today is called the
“The Alliance of Confessing Evangelicals, Inc. with the Alliance Council being made up of men such as Jerry Bridges, Sinclair Ferguson, John MacArthur, John Piper , R.C. Sproul and Albert Mohler to name a few.
Here is a
bio of Barnhouse from the Alliance.
Barnhouse himself was Reformed in his theology, and Presbyterian in his denominational affiliation.
The Angelic Conflict or as Barnhouse called it, The Invisible War, covers in detail the direct, implied, deduced and theological conclusion regarding the teaching of the fall of Satan and its co-terminus ending with human history. I have imbedded links regarding Barnhouse and it is worth some time invested for discovery. He is a Reformed theologian received and praised by the men mentioned above. So as for his qualifications, they are not just that of a minister of the Word but one recognized by other leaders in Reformed theology.