***But relying on your own personal view of Scripture is?***
You accuse others of subjectivity in interpreting the Scriptures.
Is not your own understanding of the Magesterium based on your subjective opinion of what they mean?
I believe CTID would respond, "We have the historical tradition of the Church." Personally I think this is flawed reasoning because:
2) The RCC "tradition" argument IMO doesn't make sense based upon the tradition of the RCC itself. The early church fathers knew there was a distinct difference between the inspired scriptures and other writings. Thus they composed the Bible. Yet as soon as one starts to look at inspired scriptures then "tradition" is brought in and forget sola scriptura. Ironically, church tradition says there is a difference between the writings yet this distinction is ignored in favor of "tradition".
This view on tradition has lead the RCC into error IMHO. For example, the Council of Trent accepted the Apocrypha as inspired; something the early church rejected but treated as an Appendix. What did the CoT know 1000 years later that the early church fathers didn't? Where was the reliance on tradition of the early church fathers? Rather inconsistent if you ask me.
Irenius stated that if a heathen was converted and heard heresy spoken from the pulpit without having the word of God, he would be so convicted that he would plug his ears and run the other way. Think what he could do with the word of God. I would agree.