I would not be so legalistic as to claim that there are no saints among the Church of Christ, or Catholics or ...
But that does not mean I endorse the errors taught within those denominations.
It also does not mean that I think all in any denomination are all saints.
Never mind the Church of Christ, but Catholicism is another religion, as well as Unitarian Universalism, and Progressive Christianity. It sure sounds like you need to read a book on the essentials of the faith.
Essential Doctrines on the Christian Faith by RC Sproul
My review of it.
This book is great for the new Christian, or for those wanting to sharpen up on understanding basic doctrines, or for those wanting to mature in their walk with Christ. The book is written from a Reformed point of view, but by no means does the author claim the book is only for Reformed, or that only Reformed know the essentials of the faith. Its a bit less detailed as the book "Everyone's a Theologian" but it covers many of the same topics. The book covers essential Christian doctrines such as:
Divine Revelation
The Nature and Attributes of God
The Trinity
The works and decrees of God
Jesus Christ and his divinity, humanity, the virgin birth, etc.
The Holy Spirit
Human beings and the fall, original sin, Satan, demons, syncretism, etc.
Salvation or soteriollogy
The church and sacraments
The end times
Spirituality and living in this age (Christian living).
You may want to read the book cover to cover, or just read the topics that you need to refresh on. As for me I love evangelism & apologetics, and books like this one are quite helpful because it defines what a Christian really is. I have spoken with many that claim the name of Christ, and claim the name of Christian, yet deny the Trinity, deny original sin, deny the virgin birth, deny the gospel, or some other vital doctrine. Can someone be a christian and yet deny these doctrines? Only God knows for sure but this book will help you grasp the fundamentals of the faith. My only gripe about this book is the lack of a topical index in the back, but besides that a book that every christian should have.