Grace and peace are the two things the authors of the New Testament most consistently emphasize in their greetings to the believers to whom they wrote. Those authors, inspired by the Holy Spirit, wanted their readers to know that grace and peace are the most basic and most valuable possessions they have as believers in Jesus Christ.
The salutation "Grace and peace to you from God our Father, and the Lord Jesus Christ," or some close form of it, occurs in 16 of the 27 New Testament books. It is Paul's usual salutation, but it is not unique to him. Peter also uses it in both of his letters:
Peter, an apostle of Jesus Christ, to the strangers scattered throughout
Pontus, Galatia, Cappadocia, Asia, and Bithynia, elect according to the
foreknowledge of God the Father, through sanctification of the Spirit, unto
obedience and sprinkling of the blood of Jesus Christ: Grace unto you, and
peace, be multiplied.
(1 Peter 1:1-2)
Simon Peter, a servant and an apostle of Jesus Christ, to them that
have obtained like precious faith with us through the righteousness of
God and our Saviour Jesus Christ: Grace and peace be multiplied unto
you through the knowledge of God, and of Jesus our Lord...
(2 Peter 1:1-2)
...as does John in his second epistle and in the Apocalypse:
The elder unto the elect lady and her children, whom I love in the truth;
and not I only, but also all they that have known the truth; for the truth's
sake, which dwelleth in us, and shall be with us for ever. Grace be with
you, mercy, and peace, from God the Father, and from the Lord Jesus
Christ, the Son of the Father, in truth and love.
(2 John 1-3)
John to the seven churches which are in Asia: Grace be unto you, and
peace, from him which is, and which was, and which is to come; and from
the seven Spirits which are before his throne; and from Jesus Christ, who is
the faithful witness, and the first begotten of the dead, and the prince of
the kings of the earth. Unto him that loved us, and washed us from our sins
in his own blood...
In his lectures on Galatians, Luther has this to say about grace and peace:
Grace and peace—these two words embrace the whole of Christianity. Grace forgives sin, and peace stills the conscience. The two devils who plague us are sin and conscience, the power of the Law and the sting of sin (1 Cor. 15:56). But Christ has conquered these two monsters and trodden them underfoot, both in this age and in the age to come. The world does not know this; therefore it cannot teach anything sure about how to overcome sin, conscience, and death. Only Christians have this kind of teaching and are equipped and armed with it, so that they can overcome sin, despair, and eternal death. It is a teaching that is given only by God; it does not proceed from free will, nor was it invented by human reason or wisdom.
These two words, "grace" and "peace," contain a summary of all of Christianity. Grace contains the forgiveness of sins, a joyful peace, and a quiet conscience. But peace is impossible unless sin has first been forgiven, for the Law accuses and terrifies the conscience on account of sin. And the sin that the conscience feels cannot be removed by pilgrimages, vigils, labors, efforts, vows, or any other works; in fact, sin is increased by works. The more we work and sweat to extricate ourselves from sin, the worse off we are. For there is no way to remove sin except by grace. This deserves careful notice. For the words are easy; but in temptation it is the hardest thing possible to be surely persuaded in our hearts that we have the forgiveness of sins and peace with God by grace alone, entirely apart from any other means in heaven or on earth.
Because the world does not understand this doctrine, it neither can nor will tolerate it. It brags about free will, about our powers, about our works—all these as means by which to earn and attain grace and peace, that is, the forgiveness of sins and a joyful conscience. But the conscience cannot be quiet and joyful unless it has peace through this grace, that is, through the forgiveness of sins promised in Christ. Many have worked hard, inventing various religious orders and disciplines, to find peace and a quiet conscience; but instead they have plunged even more deeply into even greater misery, for such tactics are merely ways of multiplying doubt and despair. Therefore your bones and mine will know no rest until we hear the Word of grace and cling to it firmly and faithfully.1
All believers should have that grace and peace - the grace and peace given by God through Jesus. I have that grace and peace today, and I know it to be of great power. I did not have that grace and peace as a Pentecostal, and that is why I left Pentecostalism for Lutheranism. It had become obvious to me that Pentecostalism was not delivering grace and peace, and in fact, it was not even delivering that which it claimed to deliver, power to do signs and wonders.
The consciousness of this lack (often suppressed to varying degrees) results in the instability and insecurity that I myself knew in Pentecostalism. This ignorance leaves Pentecostals open to chasing after every "ministry" where signs and wonders are said to be occurring. They accept every oddball doctrine out there if only the preachers of it are producing signs and wonders or powerful emotional experiences said to show the presence of God. As a result Pentecostals frequently crash and burn when those doctrines lead them right outside of Biblical faith and into some very dangerous practices in order to sustain what they think is the demonstration of God's power.
Or they think they aren't "yielded enough," haven't given up enough of themselves or their possessions, or must do more works of self-denial to prove themselves desperate enough in order to claim what they think are the only true marks of genuine faith. So much dependence on themselves instead of on Christ's finished work for them!
Pentecostals always think they haven't done enough or prayed enough because they aren't experiencing God's presence in the way they expect - the false way taught by fanatical, misled Pentecostal preachers. They live under a continual burden of guilt because the signs and wonders they expect from the model of Christianity they have been taught should be "normal" never in fact happen, except in reports from third world countries (which they don't personally know are really true anyway) and in crusades where emotions are whipped up by revivalistic techniques that can't be sustained in everyday life.
This is why Pentecostalism is not healthy, why I left it, and why I continue to say that it was a major wrong turn in the history of the visible church. The authentic power of signs and wonders was only temporary. Looking for the identical thing today is a mistake. Demonstrations of that kind of power served to authenticate the apostles as true ministers of the Gospel of Christ and to establish the church before the written New Testament existed. The time for those kinds of signs and wonders is past - we now have the Word's authority in the written New Testament. The power it delivers in the grace and peace of Jesus through faith in him and in his Word is the permanent power of God's church.