“Because I was baptized as a Catholic and raised as a Catholic, even though I now reject central doctrines and teachings and choose membership in another denomination am I still officially a Catholic?”
It depends on what you mean by “officially.”
It's quite likely that if you're no longer registered in a parish that you're no longer counted as a Catholic. Thus, when the Church says that there are sixty-umpteen-million-and-so-many-hundreds-of-thousands of Catholics in the United States, it's quite likely that you're not part of that number. Our parish purges its rolls every couple of years, and once you're out, you're out. If the pastor doesn't see you around at Mass on a regular basis, or if the accountant doesn't note that you're giving anymore to the parish, you're likely to be purged from the rolls. If you don't re-register in another Catholic parish, then you're no longer officially counted as a Catholic.
However, juridically and ontologically, you're still a Catholic. For all eternity. That means that you're still subject to Catholic canon law, and it means that the mark on your soul that makes you Catholic will persist for all eternity.
In this life, unless someone comes back to the Church, it probably doesn't mean much. It's not likely that a fallen-away Catholic will care much about Catholic canon law or the rulings thereof, so what's the difference?
In the next life, if the Church turns out to have been right all along, and the fallen-away Catholic, well, not so much so, then the consequences may not be so insubstantial.
sitetest
Could you point me in the direction of the scripture that says baptism leaves a denominational mark on your soul or any mark??