The word faith, as used in the New Testament, often refers to an individual's faith. An individual's level of trust. We can read of strong faith (such as that of the woman in Matthew 15 who went to Jesus, asking that her daughter be healed). We can also read of weak, or little, faith (such as those in Matthew chapter 8 who, while out on a boat and caught in a storm, were afraid they would perish.)
At other times, the word faith refers to the collective body of teachings found within the New Testament. The system of faith. Acts 6:7 speaks of those who were obedient to the faith. Galatians 1:23 speaks of Paul preaching the faith. Christians have a responsibility to defend the faith. Jude 3.
There is one faith. Ephesians 4:5. That's singular. You may hear someone, in describing another person, say "He is of the Baptist faith" or "He is of the Methodist faith." The Bible never speaks of a multiplicity of faiths. Only when we discard the teachings and traditions of men, and instead follow the one faith, the one body of teachings found within