The OT Saints were saved by this same gospel… the “good news” that God would send His Messiah.
"And the scripture, foreseeing that God would justify the heathen through faith,
preached before the gospel unto Abraham, saying, In thee shall all nations be blessed." Galatians 3:8
I quote this stuff because, as I come across them, I believe they contain solid, sober stuff that we might learn from, but also so we can just pick them up and Preach from them.
First from:
"I. The agreement between Salvation in the Old Testament and New Testament:
"e. In the blessings of
the Manifestation and Administration of the Covenant of Grace;
"They are the same under both Administrations.
"Salvation and Redemption by Christ is the great blessing held forth and enjoyed under the one as under the other,
#2Sa 23:5 Heb 9:15.
"Justification by the Righteousness of Christ, which the Old Testament church had knowledge of, and faith in, as well as the new,
#Isa 45:24,25 Ro 3:21-23.
"Forgiveness of sin through Faith in Christ, all the Prophets bore witness to; and the saints of old, as now, had as comfortable an application of it,
#Ps 32:1,5 Isa 43:25 Mic 7:18 Ac 10:43.
"Regeneration, Spiritual Circumcision, and Sanctification, were what men were made partakers of under the First, as under the Second Administration of the Covenant,
#De 30:6 Php 3:3.
"Eternal life was made known in the writings of the Old Testament, as well as in those of the New; and was believed, looked for, and expected by the saints of the former, as of the latter dispensation,
#Joh 5:39 Heb 11:10,16 Job 19:26,27.
"In a word, they and we eat the same Spiritual Meat, and Drink the same Spiritual Drink, for they drank of that Rock that followed them, and that Rock was Christ,
#1Co 10:3,4."
...
Then, about the necessity of the Gospel to be Preached:
"2c. Thirdly, The Instrumental Cause, or means of Conversion, is usually the Ministry of the Word; sometimes, indeed, it is wrought without the Word, by some remarkable awakening Providence or another, and sometimes by reading the Scriptures; but, for the most part, it is through the Preaching of the Word; hence ministers are said to
"turn many to righteousness";
"and the apostle Paul says, he was sent by Christ into the Gentile world, to
"Turn men from darkness to Light, and from the power of Satan to God";
"and this is done both by the Preaching of the Law and of the Gospel;
"the law of the Lord is perfect, converting the soul", #Ps 19:7 though perhaps not the Law, strictly taken, but the whole Doctrine of the Word is there meant;
"however, the Preaching of the Law is made use of by the Spirit of God to Convince of sin; for
"by the Law is the knowledge of sin"; and by means of it, when it enters into the heart and conscience, under His Influence, sin is made to appear exceeding sinful, and the soul is filled with great distress on account of it;
"for the
"law worketh wrath"; though some take this to be rather preparatory to Conversion than Conversion itself, which may be better ascribed to the Gospel;
"and, indeed, the receiving of the Spirit, and His Graces, and particularly Faith, are attributed to the Preaching of the Gospel, and not to the Law, as the means thereof;
"Received ye the Spirit by the works of the law?" that is, by Preaching the Doctrine of Obedience to it;
"or by the hearing of Faith?" that is, by the Doctrine of the Gospel, Preaching Faith in Christ; which is therefore called
"the word of faith", and by which it comes;
"for
"faith comes by hearing, and hearing by the word of God",
#Ga 3:2 Ro 10:8,17 but then the Preaching of the Word of the Gospel is not sufficient of itself to produce the Work of Conversion in the heart; men may hear it, and not be Converted by it; nor receive any benefit, profit, and advantage through it;
"if it comes in Word only, and not with the Demonstration of the Spirit, and of Power; and when it is Accompanied with the Power of God; or is made the Power of God unto Salvation, even then it is only an Instrument, and not an Efficient; for
"who is Paul, or who is Apollos, but ministers, or instruments, by whom ye believed?" #1Co 3:5