Are Zechariah's verses an accurate presentation of what was historically called "The Social Gospel"? How does it relate to the Gospel of Grace?

>Thus speaks the LORD of hosts, Execute true judgment, and show mercy and compassions every man toward his brother; and oppress not the widow, nor the fatherless, the stranger, nor the poor; and let none of you imagine evil against his brother in your heart. (Zechariah 7:9-10) Although this is an Old Testament quotation, these admonitions seem to be repeated throughout the New Testament as well. (Matthew 25:31-46) >Pure religion and undefiled before God and the Father is this, "To visit the fatherless and widows in their affliction, and to keep himself unspotted from the world. (James 1:27) Is the modern emphasis by Evangelical and Reformed churches on "Salvation by faith alone through grace alone"---and just saying a "sinner's prayer" for salvation---giving a wrong impression as to what the Christian faith is all about? Should the "discipleship decision" include acceptance of the "social gospel" ,as well as, acceptance of the Apostles Creed (or denomination's creed)? And is Zechariah's verses an accurate presentation of what has historically been called "the Social Gospel". ***Is it non-essential in today's presentation of the Gospel of Grace. (A different gospel? Galatians 1:6-7), or is it an essential part of the evangelical Gospel?*** Is what is called "the Social Gospel" legitimate today, if it doesn't surplant the "Gospel of Grace" for salvation? We are basically seeking a critique of the present status of "the Social Gospel idea" in modern Protestantism denominations---and in actual preaching.