It’s called the gift of Faith. It is by Faith that we are saved, and it is by Faith that we know what to believe.
That is simply superficial. Faith in something must be based upon something.
the true Church is distinguished from false churches by four marks; it is one, holy, catholic, and apostolic. Any decent Catholic catechism would explain precisely what those terms mean.
So your assurance that Rome is holy, catholic, and apostolic is based on what the Catholic catechism says?
No, there is nothing prior to the gift of Faith. Thinking that Faith is established upon some prior basis, like human reason, or private interpretation of the Sacred Scriptures, is a form of rationalism, and it is the principle fault of protestantism. So you are hitting the nail on the head here, if you can understand this fundamental difference between the Catholic view of Faith and the protestant view, you will be a long way towards making an informed choice.
Any “church” can be measured by the four marks. This is an example of using human reason as a negative rule of Faith, reason does not tell you what you must believe, but it can tell what does not belong. St Francis de Sales covers this in exquisite detail in his book “The Catholic Controversy”.
When I walk into a church in Louisville, and see that it is guarded by centurions from the third century (short little guys!!), I get the immediate sense that the Catholic Church is a family, a family that is one, holy, universal, and apostolic. When I receive the Body of Christ in holy communion, I know that He is with us all days, and that the gates of hell will never prevail against His bride, the Church.
If you think my Faith is superficial, you should probably read my other posts. The one thing that must be kept in mind, despite all the caterwauling that comes from outside the Church, the amount of things one must assent to in matters of Faith and Morals is quite small. As He said, My yoke is easy, and My burden is light.