Salvation by “faith alone” limits God’s grace

Advocates of salvation by faith alone have, in the past, argued that anything else is unbiblical legalism, and so makes void God’s grace. This is entirely mistaken.
The reason it limits God’s grace, is that it removes the crucial change that grace causes. Faith doesn’t simply give us the password to heaven, no matter how good the creeds professed. In God’s grace, we are made Godly. By our faith in God, we let in God’s grace, that proceeds to fundamentally change us. God’s grace takes over us, as we allow Him, and fills us with grace also, so that we can say with Paul,

with Christ I have been crucified, and live no more do I, and Christ doth live in me; and that which I now live in the flesh—in the faith I live of the Son of God, who did love me and did give himself for me;
Galatians 2:20

And,

Not having my righteousness, which is of law, but that which is through faith of Christ—the righteousness that is of God by the faith, to know him, and the power of his rising again, and the fellowship of his sufferings, being conformed to his death, if anyhow I may attain to the rising again of the dead.
Philippians 3:9-11

Don’t mistake it for legalism. It is through God’s grace that the change is had. It is not by man’s effort that salvation is reached (though each can refuse or accept).

for if by the offence of the one the death did reign through the one, much more those, who the abundance of the grace and of the free gift of the righteousness are receiving, in life shall reign through the one—Jesus Christ.
Romans 5:17

It is God’s gift, that those of the true faith will imitate Him they have faith in. It is only natural. [rereading this post, I feel the need to note that it isn’t “only natural”, but is also supernatural]

Jesus talked a lot about what to do to be forgiven and enter the Kingdom of God. You could argue it was all mere legalism before he had taken our place upon the cross, but that would make him irrelevant to us in all apart from his crucifixion and resurrection; It would be a far shorter good news. But we cannot remove Jesus’ redeeming work from his holy teachings.
Anyway, Jesus had to deal with legalism himself(Matthew 9:13, Mark 2:27). Jesus already acknowledged that a list of dos & do nots was insufficient, and mercy was required, so that God also would be merciful.

‘For, if ye may forgive men their trespasses He also will forgive you—your Father who is in the heavens;’
Matthew 6:14

Jesus explains the way he will be manifested to us,

Judas saith to him, (not the Iscariot), ‘Sir, what hath come to pass, that to us thou are about to manifest thyself, and not to the world?’ Jesus answered and said to him, ‘If any one may love me, my word he will keep, and my Father will love him, and unto him we will come, and abode with him we will make;’
John 14:22-23

That the Son, and the Father, and the Comforter will make abode with us is brilliant news. This requires us to love Jesus, and so keep his word. And the Father, and the Son, and the Comforter, will make us holy.

This idea of justification by faith alone is harmful to the Church, because it ignores God’s holy gift.

But I must make this crystal clear: I am not advocating legalism. It is the God-given, miraculous transformation that saves us, coming through faith.

Having been declared righteous, then, by faith, we have peace toward God through our Lord Jesus Christ, through whom also we have the access by the faith into this grace in which we have stood, and we boast on the hope of the glory of God.
Romans 5:1-2

Any deeds are the natural [and again, supernatural] effect, and outward manifestation of God’s seed within us (1John 3:9). They are not what earn salvation.
The repentant criminal on the cross at Jesus side did no act to save himself but trust Jesus and be transformed.

Rejoice in God’s gift. He gives you Himself, to make you holy.

God bless you.

P.S.
the reason I felt the need to write about this doctrine is that it is so much less than the truth.
I don’t know how common this Lutheran idea is today, but I have come across it a couple times, and it seemed to have general acceptance. The problem is, it makes God’s grace weak, in failing to make us holy inside; and convenient, in changing little of our lives. Also, it isn’t Biblical.
One time I came across this doctrine was in a church drama, set in the airport to heaven. A man in a suit went to get on the plane and mentioned all his good work, but wasn’t allowed on because of his passport not being good enough. Then a criminal was allowed on, using Jesus’ passport. It seemed nice to get on, but I didn’t get why this is a good system. The point of passports is for accurate ID. It didn’t seem right to me, but I figured it was a bad analogy.
I might have misremembered, as this was years ago, and I didn’t listen in Church much back then.
I didn’t suspect it was maybe wrong for years.

God bless you.

P.P.S.
Earlier today I was reading about sanctifying grace on the Catholic Encyclopedia website, and that really helped clarify this for me, and provide lots of Bible verses relevant to the matter. A lot of thanks to them.
I had been thinking along similar lines on salvation, though I was phrasing it as “Does God believe in you?” which is far less Biblical language. What I had been saying is that if God doesn’t know you, you are turned away, and I took this to mean if God believes you’re good for him. I was also saying that true faith leads to being the kind of person God believes in.
I’m glad I waited rather than publishing that before I was aware of the more complete answer. Thank God because that post could have been very misleading.

God bless you.