You are free to believe whatever you choose.
Sure everyone is.
The problem is, all the made up stuff of Catholicism isn’t going to do anyone a lick of good.
God revealed to us in Scripture what mankind needs for salvation. People certainly are free to exchange that for the doctrines of men, to the peril of their soul.
If you wish to put the catechism ahead of Scripture, it’s your prerogative.
But you can’t say you weren’t told.
Was that St. Paul's answer when the jailkeeper asked:
The jailer called for lights, rushed in and fell trembling before Paul and Silas. He then brought them out and asked, “Sirs, what must I do to be saved?”
They replied, “Believe in the Lord Jesus, and you will be saved—you and your household.” Then they spoke the word of the Lord to him and to all the others in his house. At that hour of the night the jailer took them and washed their wounds; then immediately he and all his household were baptized. The jailer brought them into his house and set a meal before them; he was filled with joy because he had come to believe in God—he and his whole household. (Acts 16:29-34