Ananias and Sapphira were true Christians as they were with the apostles and giving money toward their cause. The ones that did not become Christian left them because they were not of them. I think before the apostles took money from anyone, they would have had to have known that they were baptized followers of Christ. Would they take money from a Pharisee? John the baptist would not even baptize them and said, 7 [j]Now when he saw many of the Pharisees, and of the Sadducees come to his baptism, he said unto them, O generation of vipers, who hath forewarned you to flee from the anger to come? MATTHEW 3:7