Paul said, “Believe in your heart that God has raised Him from the dead, and you will be saved.” Do you not think that “faith” is what he meant when he used the word “belief”? And doesn’t that mean that faith is enough to save us, without works (Sola Fides)?
First, Paul did not say “Believe in your heart that God has raised Him from the dead, and you will be saved.” Paul said,
“9 ܘܐܢ ܬܘܕܐ ܒܦܘܡܟ ܒܡܪܢ ܝܫܘܥ ܘܬܗܝܡܢ ܒܠܒܟ ܕܐܠܗܐ ܐܩܝܡܗ ܡܢ ܒܝܬ ܡܝܬܐ ܬܚܐ ܀”,
…and arguing over similarities of certain words in English after passing them through Greek is, with all due respect, a pointless exercise. Also note that there is more to Paul’s directive:
“9And if you will confess with your mouth Our Lord Yeshua, and you will believe in your heart that God has raised him from the dead, you shall have life.”
So, already we have established that simple belief MUST be accompanied by an act to have any meaning. Belief in itself is not faith. Do we say that someone is a faithful spouse because they believe that they are married, or because they conduct themselves in a way that is true to the ideal of marriage? Do we say that a recording is faithful because it believes in the original production, or because it truly looks or sounds like the original? As James would say, “ 19You believe that God is One; you do well; the demons also believe and tremble.”
Also, look at Matthew 14:
28And Kaypha (Peter) answered and he said to him, “My Lord, if you are He, command me to come unto you on the water.” 29And Yeshua said to him, “Come”, and Kaypha went down from the ship and he walked on the water to come to Yeshua. 30And when he saw the wind was violent, he was afraid, and he began to sink, and he raised his voice and he said, “My Lord, save me!” 31And immediately Our Lord stretched out his hand and he held him and said to him, “Oh small of faith! Why did you doubt?” 32And when they came up into the ship the wind stopped. 33And those who were in the ship came and they worshiped him, and they said, “Truly, you are The Son of God!”
The boat was full of the Christ’s disciples. They all BELIEVED in the Christ. But only Peter had a little FAITH, and walked out on to the water (even though he failed eventually).