When describing my personal thoughts back in a few years ago.
Should I use:
One thing I was sure though, is that ...
One thing I was sure though, was that ...
To me, it sounds more correct to use "was", because it's some thoughts from the past. But I understand when describing a fact, such as the "sun goes up from the east", you should use the present tense.
If I still hold the thought I had back then, would it be OK to use "is" instead of "was"?