how can i help someone i know is homeless?

i know someone thats homeless, shes sleeping outside one of the churches here, she had her birthcertificate stolen and id, she did get another birthcertificate, just wondered if she sleeps outside a church why cant they let her in instead of making her sleep outside and getting frostbitten, i cant take her in to my place cause im in an apt and they'll just kick both of us out. why dont people at church act like christians and take her in? she dont like the shelters, guess she has a hard time with the people there,so why are people not taking her in? i think thats mean.