Excuse me. Protestants have Catechism as well. There is quite a bit of difference between memorizing doctrinal beliefs and study to show yourself approved.
There is nothing easier than convincing oneself that what you believe is true and "guided" by the Holy Spirit.
Except perhaps having someone tell you what to believe because THEY are guided by the Holy Spirit.
Well, here, I will agree with Harley. However, I will point out that Catholics ALSO do not place memorization of the catechism as important, above practice. The whole point of doctrines is to give us an objective grounding in the experiences of God that we all have claimed to have. Experience is subjective. Our experiences can mean quite anything. But with the solid grounding of the Church, the pillar of truth, we KNOW that Jesus Christ, Whom we experience, is the second person of the Trinity, and was born of a virgin woman... The catechism defines our experiences in truth.
Regards