I'd just like to say I like Shakira's POV. Allah's cause is all important.
The Sabi perspective on Christian (and any other) doctrine is that anything which does not contradict what came before it in the scriptures is acceptable. Hence the way Sabi`een understand the Quran is different, even though it is a blessing for us to believe in it. However, since each book is perfect at the time of its revelation, it is enough to follow only what has come in the latest revelation if one so wishes, but then one would be misguided if one did not in that case also study the sunnah of the prophet that came with it.
The Zaboor do not contradict the Torah, neither the Injeel contradict these, neither does the Quran contradict any of these. If Jews allow their philosophizing to make it impossible for anything to come after the Torah then that is problematic. Similarly if any religious group allows its interpretation of its scriptures to become so dogmatic that they can not allow a literal agreement between their own scripture and a later scripture to be acceptable then that is also problematic. If Christians make their interpretation of Injeel irreconcilable with the Torah and Zaboor then that is also problematic. Likewise for Sabi`een, interpretation of the Quran which does not at the very least harmonise with the previous scriptures is also problematic for us (especially as we see that this certainly need not be the case at all).
The major problem with most Christians is that they have forgotten that Allah (greek TonTheon) is God's Name, and they pray to God's throne and God's spirit in total ignorance of God's Name. All of their other mistakes come from this simple yet incomparable mistake. -At least that is what it looks like to me.
:brother: