Jon, Biblical in the meaning all doctrine is derived from the 66 books of the Bible. Catholic, Orthodox,Coptic, etc… doctrine can come from the Bible, Apocrypha, Tradition, etc… I’m not an expert, but I think that line of distinction can be drawn between the Anglican Church and Lutherans.
Essential - what gets you to Heaven. LCMS is clear. Baptism is not a requirement of salvation.
Straight from the LCMS Website -
Statement of Scriptural and Confessional Principles - The Lutheran Church—Missouri Synod
Section I
“We believe, teach and confess that Jesus Christ is our Savior and Lord, and that through faith in Him we receive forgiveness of sins, eternal life and salvation.
We confess that “our works cannot reconcile God or merit forgiveness of sins and grace, but that we obtain forgiveness and grace only by faith when we believe that we are received into favor for Christ’s sake, who alone has been ordained to be the mediator and propitiation through whom the Father is reconciled” (AC, XX, 9).” (emphasis. added)
The LCMS is not as dogmatic on Confessions as you think they are - Secton IV, 2
“We recognize, for example, that subscription to the Lutheran Confessions
does not bind us to all strictly exegetical details contained in the Confessions, or even to the confessional use of certain Bible passages to support a particular theological statement.”