“And don’t presume to say to yourselves, ‘We have Abraham as our father.’ For I tell you that God is able to raise up children for Abraham from these stones!”
Matthew 3:9 HCSB
The Sadducees and Pharisees who came to spy on John the Baptist that day were greeted with a firm warning. It does not matter that you claim Abraham as your father, that will not spare you. The Pharisees and Sadducees believed in a spiritual genealogy that provided salvation for them.
However, John the Baptist preached repentance was individualized. The nature of salvation rested upon person not genealogy. I have heard individuals claim to be Christians because they come from a family that was active in the faith. When they do this they are assuming a spiritual genealogy as a means for salvation. This is the same belief the Pharisees and Sadducees held, and we need to point it out that God does not care if your parents were Christians, but do you know Him personally.