Actually, Catholicism adheres to the basic tenets of Christian orthodoxy as defined by the Creeds (which, btw, are based on scripture). This is the SAME orthodoxy (and the same creeds) observed by the vast majority of Christendom.
The groups and individuals who claim that the Roman Catholic Church is "not Christian" have either:
A. created their own "orthodoxy"
B. fail to understand what orthodoxy is and how it is important in the history of the Church OR
C. understand orthodoxy, accept orthodoxy, but elevate non-essential doctrines to support their dislike and to make the claim of "not Christian"
For example, prayer to the saints is a non-essential doctrine.
I think it is useful for Christians to familiarize themselves with the Creeds (Apostles, Nicene, and Athanasian). Additionally, it's probably also useful for people to recognize that the vast majority of doctrines that they find objectionable within the RCC are also present within the Orthodox Church, the Anglican Church, the Lutheran Church, the Episcopal Church, some sects of Presbyterianism, some sects of Methodism, etc. So, it might be important for people to decide how small they want God's kingdom to be.
The groups and individuals who claim that the Roman Catholic Church is "not Christian" have either:
A. created their own "orthodoxy"
B. fail to understand what orthodoxy is and how it is important in the history of the Church OR
C. understand orthodoxy, accept orthodoxy, but elevate non-essential doctrines to support their dislike and to make the claim of "not Christian"
For example, prayer to the saints is a non-essential doctrine.
I think it is useful for Christians to familiarize themselves with the Creeds (Apostles, Nicene, and Athanasian). Additionally, it's probably also useful for people to recognize that the vast majority of doctrines that they find objectionable within the RCC are also present within the Orthodox Church, the Anglican Church, the Lutheran Church, the Episcopal Church, some sects of Presbyterianism, some sects of Methodism, etc. So, it might be important for people to decide how small they want God's kingdom to be.