Faith alone has always been the means for justification.
Paul uses Abraham to illustrate this point: 'For what saith the scripture? Abraham believed God, and it was counted unto him for righteousness'. In verses 4-5 Paul provides an example for us to think about. 'Now to him that worketh is the reward not reckoned of grace, but of debt. But to him that worketh not, but believeth on him that justifieth the ungodly, his faith is counted for righteousness. Even as David also describeth the blessedness of the man, unto whom God imputeth righteousness without works,' Romans 4: 3-6
Verse 5 reads, 'But to him that worketh not, but believeth on him that justifieth the ungodly, his faith is counted for righteousness,' Romans 4:5, KJV. Joseph Smith changes the scripture to read, 'But to him that seeketh not to be justified by the law of works, instead of to him that worketh not, and tweaks the analogy Paul was making about the one who works vs the one who does not.
He also changes the scripture to read, but believeth on him who justifieth not the ungodly instead of him that justifieth the ungodly- his faith is counted for righteousness,' Romans 4:5, JST.
Joseph maligned the scripture when he added the word not. Paul repeats himself twice to affirm that indeed God does justify the ungodly as shown in Romans 5:6-8 that 'Christ died for the ungodly,' and 'God demonstrates His own love toward us, in that while we were yet sinners, Christ died for us. Anyone who is familiar with Paul's writing knows Joseph is fiddling with God's word. It is not in keeping with the gospel of grace Paul teaches. It is another gospel.
The Book of Mormon states, 'we know that it is by grace that we are saved, after all we can do.' 2 Nephi 25:23 Realistically, all we can do is appeal to God to remove sin and be declared righteous by faith. It is not in the realm of possibility to save ourselves because as it is written in Psalms, 'there is none righteous no, not one.' The Book of Mormon teaches you have to: 'deny yourselves of all ungodliness; and if ye shall deny yourselves of all ungodliness, then is his grace sufficient for you.' Moroni 10:32
If there is power in the word then I can receive the assurance of his grace. It is in the means by which we are made righteous that we are in disagreement. That means is through faith alone in Jesus Christ.
Just as with the Jews, there is a wall that separates those who have a zeal of God but not according to knowledge.. Paul now tears down the wall of partition they've erected. Christ united Jews and Gentiles into one people when; 'In Christ Jesus ye who sometimes were far off are made nigh by the blood of Christ. For he is our peace, who hath made both one, and hath broken down the middle wall of partition between us.' Ephesians 2:14
We do a lot of work. But none of it justifies us before God. The author of Ecclesiastes says, 'Then I looked on all the works that my hands had wrought, and on the labour that I had laboured to do: and, behold, all was vanity and vexation of spirit, and there was no profit under the sun.' Ecclesiastes 2:10-11.
Why does the author of Ecclesiastes say this? Because salvation by your own works of righteousness is futile.