From a Catholic perspective, the chances of our having doubts about the authenticity of Scripture are much less likely, since it was the Catholic Church that canonized which books are included, in the first place. At the time the list was first proposed, the authenticity of those books was much more fresh in the minds of the Early Fathers. They knew which books were already being used in the liturgy of the Mass, particularly in Rome, which would have been closer to the teachings that came from Peter. They knew which were the oldest, where they came from and who wrote them.
This is all based on the Sacred Tradition of the Church, which concerns what was passed down orally from the Apostles, that was not contained in the Scriptures, themselves. This is also the major difference between Catholicism and Protestantism. Protestants rejected Sacred Tradition, which is where many Catholic Doctrines, that were also rejected by them (such as Purgatory, praying to the Saints, devotion to Mary, etc.), derived their basis. They came from the teachings of the early Church Fathers, who originally received them from the Apostles or their direct disciples.
This is also why Apostolic succession is so important in determining the truth of what should be believed by all Christians. The practice of “the laying on of hands” which began with the Apostles, has continued in an unbroken chain ever since that time. That’s how the full power of the Holy Spirit is transferred from one person to another. Once that chain is broken, the original connection is lost until it can be repaired, and reattached to the original chain.
Someone having personal doubts about certain aspects of the faith, is an entirely different story. We all have struggles with that from time to time. But, most Catholics firmly believe that as long as we hold onto whatever the Church teaches us about faith and morals, we can never go wrong. We have a solid guarantee from Jesus that the Church will always be led into all truth by the Holy Spirit, who will protect the Church from teaching error, even though individuals within the Church are certainly capable of doing that on their own.