See Romans 10:9.
He already took me into HIS heart the day he took my sins on the cross and died for me - I took Him as my Savior at the tender age of 6 and KNOW it is by HIS GRACE I have been saved, not by works should I even boast. (Eph 2:8,9)
More appropriate would be 2 Thessalonians 3:5 (NIV)
Exactly. The confession of our mouth that Jesus is Lord and that God raised Him from the dead cannot be empty words, but rather an expression of true faith. Ephesians 2:8-9 states that it is that faith, by grace, that saves us. Many people give intellectual assent to the Gospel, but have not allowed Jesus to be Lord of their life.