Yes it is. Entirely. To us, that is. It is free to us, because the price has been paid, in full, for all time, by God Incarnate, by His Infinitely meritorious Death upon the Cross. Our salvation cost God everything - it means giving up His own Son, the Son Whom He loved before the foundation of the world, the Son Who is the Heir of the ages, the Son Who is infinitely pleasing to Him. And the Father gave up His own Son, not the for the righteous, but for His enemies, so as to adopt them as His sons & daughters; not because they are worthy of this, but because they are not at all worthy of it, because they deserve condemnation for their sins, & not mercy.
What could God do for sinners - us included - that He has not done ? If Heaven is not free, He is not a God of Grace; for grace is free; it is God’s free favour. So there is no more price to pay. The “gospel of salvation by meritorious works” makes grace a mere empty word. It’s just another way whereby our innate self-righteousness & longing for self-justidfication tries to use even the Good News as a means of asserting itself; of doing anything in heaven or or earth or hell but trust in & rest on the perfect, finished, all-sufficient, all-gracious, atoning, final work of Christ. There is no second Christ, no sacrifie that we can bring to complete the work of the first Christ, Who is the only Christ: His salvation is the only salvation there is. So we are boxed in: either we accept the only salvation on offer; or we don’t accept salvation at all.
Faith is by its very nature alone - it is not accompanied by good works, at all. Before we are Christ’s, we can do no works that are not bad; to deny this,is to say that those who do npot belong to Christ at all, who are not justified by His grace, produce the same works as His servants. It means that grace is not required for salvation or justification. It means that man is the author & cause of his salvation - that God is needless. Faith is alone, because grace is alone. If faith within us by the free grace alone of God be not the root and foundation of the whole of our salvation-life that is in Christ alone, for the glory of God alone, then we are, again, not saved by grace