Thank you for defining yourself.
I disagree with this part: "Scriptural authority to preach cannot proceed from such an organization" (infant-baptizing church).
Can you find where Christ gave authority to a pedobaptism institution in scripture?
Look at the Great commission! The command to "go" preach the gospel (Mk. 16:15) is given to those Christ described as "disicples" and he defines disciples as those already immersed believers who have been taught how to observe all things commanded (Mt. 28:19-20)
So where is your Biblical basis for "scriptural authority" behind such an institution? Where does the Scripture teach evangelization, baptism and inclusion of infants? Where can you find a "church" composes of infant membership?