Faith alone wouldn't save, if it wasn't for grace.
Faith means to trust, it's more than a belief. Faith without works is dead, because faith without works is vain belief.
God's will is that you trust (have faith in) his Son.
If you trust his son, you will do what he says.
If you don't, then you have no faith, irrespective of your belief in Jesus. You can believe he's the Son of God, you can believe he died for your sins. But those are in vain without faith (trust). Which is why Jesus says, not everyone who says Lord will enter the kingdom, but those who do the Fathers will: to have faith in Jesus. Many Christians say, "trust in the work done on the cross", although it's important, they cut it off there. But that alone won't save you if you neglect everything else. - As to why I'm against modern doctrines, because they were steering me in the wrong direction, when I became a believer.
There are inclusive precursors of faith, that as a whole demonstrate faith. Beginning with a mindset.
To do these things is in itself faith:
"If anyone comes to Me and does not hate his father and mother and wife and children and brothers and sisters—yes, even his own life—he cannot be My disciple. And whoever does not carry his cross and follow Me cannot be My disciple." ... "In the same way, any one of you who does not give up everything he has cannot be My disciple." If you haven't given everything up, are you saved? Your belief will be counted for nothing.
Again, re-stated by Jesus: "Jesus told His disciples, “If anyone would come after Me, he must deny himself and take up his cross and follow Me."
"Anyone who loves his father or mother more than Me is not worthy of Me; anyone who loves his son or daughter more than Me is not worthy of Me; and anyone who does not take up his cross and follow Me is not worthy of Me."
"He who receives you receives Me, and he who receives Me receives the One who sent Me."
"The seed falling on rocky ground refers to someone who hears the word and at once receives it with joy. But since they have no root, they last only a short time. When trouble or persecution comes because of the word, they quickly fall away."
So they hear the word and receive it with joy. Are they saved? No. Why? Because they had no faith. If they had faith, they would deny themselves, and in times of persecution, they would save their life by losing it for the sake of Jesus.
If you neglect these things in the opportunity given, by means of faith, then you won't be saved. This isn't to say, you won't be saved if you don't complete a set of actions. God knows the heart and how true your faith is (whether your faith has a root in good ground, if it is, then you will have fruit).
Hear what Jesus says, not what you want to hear him say. Paul paraphrases the doctrine of Jesus, that he doesn't redundantly repeat it. Many ignore what Jesus says, and therefore don't fully understand what Paul is speaking about, thus corrupting scripture. Throwing around cherry-picked verses in vain.