Could one not, while taking in the context of the time, imagine that Christianity, at it's birth, could have been considered a sect of Judaism? Was it not Jews who converted? From what I understand (and I'm not as well versed as I'd like to be) those who did not convert, chose not to because Jesus did not resemble the Messiah they wanted. Did those Jews that did convert just completely ditch the Torah? Did early Christians not incorporate their Jewish traditions? I'm just really damn curious about early, early Christianity.
Follow up question:
If I remeber correctly Christianity was considered a Jewish sect by the Romans until the religion grew. When did it excatlys stop being considered that?
Current consensus among late antique historians is that Christian and Jewish communities, despite some clear articulations of difference in Acts and a few other early writings, were actually very closely interconnected if not often indistinguishable for several centuries after Jesus' preaching. The book to start with is Border Lines, by D. Boyarin.
Another excellent, if challengingly written, book about early Christian attempts to distinguish themselves from Judaism and other groups of the Greco-Roman world is D. Buell, Why this New Race. For a similar argument with a somewhat more penetrable style, you could also see E. Rebillard, Christians and their Many Identities. Both books are about the broader question of how Christian identity fits into its late antique context, not just how it related to Judaism (for which Boyarin remains the best starting place).
All agree (though Buell takes a slightly different tack) that, before the church gained social prominence, boundary lines were typically fluid, poorly enforced, and often not a priority except when specific circumstances and events required the Christian community to articulate and create a difference from its surroundings.
Because I haven't posted an answer on here before, and I understand the strict requirements for answering, I'll just preface this by saying I have a BA in Biblical Studies from an accredited college and spent three years in seminary working on an MA in Chaplaincy, so I'm not just talking off the top of my head.
Christianity was considered a sect of Judaism at first, as you ask. That said, it wasn't long before it spread to Gentiles as well, primarily those who were already converts to Judaism, like Cornelius in Acts 10 However, the process of extracting Jewish culture and practice from it was a difficult one. Even as early as Acts 15, you can read about the conflict between "Judaizers", those who felt that circumcision and other Jewish practices should remain in the church, and those who felt that such practices had no salvific value and should not be impressed upon new Gentile believers. Even Paul fought vigorously against the incorporation of Jewish practices into Christianity, as he writes in Galatians 5 that he wished that the Judaizers would go all the way and "emasculate themselves" (the Greek reads, "cut themselves off.").