i think its easy to fall into the trap of chosing 'the right religion' as opposed to seeking god from the little we know about him.. remember religion in itself is man made... as in the creation of it.. jesus may have inspired chritsianity but we've all seen his words manipulated and distorted to support terrible things (as in all religions)..
in order to recieve salvation jesus' teachings told us to believe on him and to love others as ourselves etc etc... not to put faith in religion.. if anything jsus came to oppose the religiousity of the pharisees and their lack of love and compassion despite appearing to be bold religious figures....
our personal response to god from what we know of him (and what we seek of him) is to me the big decision as opposed to what set of rules or religion we put faith in.. i put no faith in religion as such, but a lot in god and the spiritual walk that encompasses that belief.....
i think what your sister said about not checking out other faiths could be because she fears you'll find another one to belive in etc.. which ultimately doesnt show a lot of faith on her end... altho i stand strong in what i believe i'm going to continue seeking for answers cos im far from having them all.... we are so small and cannot fathom or claim to know all the answers, even with all the effort religion makes to cancel out doubts and confusion.
we can only cling onto the rare truths we find along the way and let them guide our search.. but searching is not a result of a lack of faith.. perhaps even the opposite.. i believe that you'll understand your own faith better when you have an understanding of others.
remember that many people can be religious but have missed the boat altogether when it comes to knowing god and being spiritually connected. in the end thats the biggest thing.
sorry this was so long!! just food for thought