If you confess with your lips that Jesus is Lord and believe in your heart that God raised Him from the dead, you will be saved.
Salvation is never just a thought or a mood. It is inherently incarnational. Just as Jesus Christ is fully God and fully Man, so our faith must be enfleshed. A faith that is merely “in your heart” is like an unconceived baby or a bubble without its skin of soap. There’s no There there. On the other hand, lips that confess without faith are the lips of Judas Iscariot, kissing Christ in betrayal. But divine faith expressed in the flesh of our deeds (including the simple act of saying “I believe” with your lips) is a step we take toward participating in the divine nature (as 2 Peter 1:4 says we are to do). Today, make a simple profession of faith in Jesus our Lord — aloud. It’s of such little steps that the journey to salvation is made.