This was already addressed and avoids the question. The gift of faith has both an object and a basis, (Rm. 10:17) and the basis for your assurance that Rome is the one true church, and thus your faith really is a gift from God, is the issue, which your posts have failed to actual answer from the beginning. .
He established His [Roman] Church as another gift to us...,
That is a mere assertion, and subjectively claiming the gift of faith is not the answer.
I am not sure I can make it any more clear.
Maybe you should define what you mean by “basis for assurance”. What is the basis for your basis?
The light of Faith is a gift, much like the light of the natural reason is a gift. God made us in His IMAGE and LIKENESS, which means we have the ability to know and to love. That is, He instilled in us the first principles of our natural knowledge, without them we would be lost, being unable to abstract any universals from our experiences. We would have no ability to acquire scientific knowledge of any sort. In like manner, without the gift of Faith, we have no ability to advance in the divine science. Without first principles there can be no science. Even when we encounter a rule of Faith, like the Sacred Scriptures, lovingly compiled for us, or miracles, or the teachings of the Early Church Fathers, or teachings of the Bishop of Rome, both ordinary and extraordinary, it is our Faith which resonates when presented with Truth, it is the work of the Holy Spirit in our souls, and it is a beautiful thing. But the gift of Faith comes, not as a single virtue, no, Faith comes in a trinity of virtue, for with Faith comes also Hope and Charity. It is impossible to study the science of God, as known through revelation, without Charity.