You will note that the total accumulation of Baptists, not neglecting the great number of independent local Baptist churches unaccounted for, is at least equivalent to the number of those claiming allegiance to Roman Catholicism.
While Baptists are likely to disagree on some minor doctrinal points, in the major they are consistent with the Biblical distinctives that identify them, principally that of the ordinances of: (1) The Remembrance Supper as a figurative commemoration of the sacrificial death with resurrection to eternal bodily and spiritual life in Jesus, The Christ; and (2) the water baptism into church membership by the total immersion of the accountable, professing believer.
In addition, for all Baptists: the Holy Scriptures are the sole authority for doctrine; autonomy of the local church is a prime teaching; every regenerated beiiever is a priest of God, with none being superior to another, all under one eternal High Priest the Lord Jesus Christ; each individual having soul liberty to determine true cotrine and obedience to it, according to the Bible; that there are only two Biblical offices allotted by the Bible for the individual local assembly, those being the pastor/elder/teacher and the elected deacon(s); and finally that there is a complete separation between the human political government(s) and the visible churches on earth.
These distinctives are expressed in the acronym B.A.P.T.I.S.T.S. , an explanation of which is found in several links, one of which is
What Are the Eight Baptist Distinctives?
http://www.angelfire.com/la/jlush/baptist.html>
Being locally always autonomous and never catholic in polity, Baptists cannot and dot exist in denominational form, so to speak, although they may form an association of like-minded local churches to economically share resources, and may convene regularly for agreements as to how to perpetuate The Faith in mutual support.
Baptists are not "Protestants" since they have always been in existence from the first prototype local assembly of Jerusalem founded on the day of Pentecost in the year of Christ's death, and multiplied thus in local churches throughout the subsequent centuries. They have never believed in answering to a human government of their doings external to that of the officers appointed or elected by the local assembly, directly accountable to their Lord, of which the assembly is a representation of His Body.
(For the purpose of noting the surpassing numbers of American Baptists, and their existence separate from the American episcopacies.)
Thanks although identifying as a Cath is not necessarily the same as claiming allegiance to Roman Catholicism, since self ID Caths abound with dissent from official teaching, while a lot of Baptists are liberal.