Have you ever met someone that agrees with your prayers and speaks the right words occasionally? However, the words most of the time don’t reflect how a Christian should speak, they are anything but glorifying, and they don’t profess they believe in Jesus. God showed me that such a person might have a broken heart (out of the heart the mouth speaks). A broken heart may be the barrier to receiving Jesus as their savior.
From the heart comes faith, that leads to salvation, “that if you confess with your mouth the Lord Jesus and believe in your heart that God has raised Him from the dead, you will be saved.” Romans 10:9
Unbelief is a reflection of an evil heart (not complete and whole in Christ).
Faith and trust both come from the heart, “Trust in the Lord with all your heart, And lean not on your own understanding; In all your ways acknowledge Him, And He shall direct your paths.” Proverbs 3:5.
So, if you know someone that is struggling with believing or you are struggling with believing and proclaiming Jesus as your savior, commit your heart to God and not trust yourself, for He heals the brokenhearted (Isaiah 61:1).