Jesus said it wasn't what went into your mouth that defiled you but what came out of your mouth.
What you say, do, think, those things get you into trouble.
Christians believe they are sinners, that they fall short of the glory of God, that Jesus is the Son of God, that He is sinless, died a death on the cross, and was Resurrected. Christians believe that faith in Jesus the Christ and His Resurrection and sharing (professing) that Faith is what gets you Salvation.
"If you believe in your heart and profess with your mouth that Jesus is Lord, you will be saved."