Faith is a gift from God and it's not something you can decrease or increase by yourself. If you need more, ask for it, and God will honor your request at just the right time according to His plan and purpose for your life. We encourage you to focus on God and what He's done in your life so far as well as read His word so that you can fill your mind with the right thoughts.
You need a lot of faith in Jesus Christ, because there's no reliable evidence that he even existed. The story of Jesus is just a myth bolted together out of previous myths and stories from the Old Testament -- created in the 40's and 50's by Paul of Tarsus (who exhibited evidence of epilepsy and had delusions of Christ talking to him), the other apostles, the unknown authors of the gospels in the 70's or later, and many other people. The reliable evidence for this is overwhelming. See the links.
The mythical story of Jesus' crucifixion is a horrible story of human sacrifice. Christians even celebrate it by ceremoniously drinking his blood and eating his body. This is ritual vampirism and cannibalism.