Will all men, then, be saved through Christ as they became lost through Adam?

No. Only those who, by true faith, are incorporated into Him and accept all His benefits.

What is true faith?

It is not only a certain knowledge by which I accept as true all that God has revealed to us in His Word, but also a wholehearted trust which the Holy Spirit creates in me through the gospel, that, not only to others, but to me also God has given the forgiveness of sins, everlasting righteousness and salvation, out of sheer grace solely for the sake of Christ's saving work

 

What, then, must a Christian believe?

All that is promised us in the gospel, a summary of which is taught us in the articles of the Apostles' Creed, our universally acknowledged confession of faith.

I. Salvation Is Particular, Not Universal

A. Only believers have hope in Jesus. He came unto his own, and his own received him not. But as many as received him, to them gave he power to become the sons of God, even to them that believe on his name: Which were born, not of blood, nor of the will of the flesh, nor of the will of man, but of God. (John 1:11-13)

B. If salvation were merely a cultural or social matter, Rabbinic Israel would still control the religion of Abraham. And if some of the branches be broken off, and thou, being a wild olive tree, wert graffed in among them, and with them partakest of the root and fatness of the olive tree; Boast not against the branches. But if thou boast, thou bearest not the root, but the root thee. Thou wilt say then, The branches were broken off, that I might be graffed in. Well; because of unbelief they were broken off, and thou standest by faith. Be not highminded, but fear: (Romans 11:17-20)

C. Faith is the way in which God distributes new life. For unto us was the gospel preached, as well as unto them: but the word preached did not profit them, not being mixed with faith in them that heard it. (Hebrews 4:2)

D. The great benefits of the Christian religion belong to those who live by faith. Cast not away therefore your confidence, which hath great recompence of reward. For ye have need of patience, that after ye have done the will of God, ye might receive the promise. For yet a little while, and he that shall come will come, and will not tarry. Now the just shall live by faith: but if any man draw back, my soul shall have no pleasure in him. But we are not of them who draw back unto perdition; but of them that believe to the saving of the soul. (Hebrews 10:35-39)

E. The promise was always particular and not universal. He shall see of the travail of his soul, and shall be satisfied: by his knowledge shall my righteous servant justify many, for he shall bear their iniquities. (Isaiah 53:11)

II. Only True Faith Counts with God

A. Believers must have genuine knowledge of the truth. And this is life eternal, that they might know thee the only true God, and Jesus Christ, whom thou hast sent. (John17:3)

B. It was through propositional revelation that God reached and transformed us. Of his own will begat he us with the word of truth, that we should be a kind of firstfruits of his creatures. (James 1:18)

C. From the start, faith has been the normal context for grace. For the promise, that he should be the heir of the world, was not to Abraham, or to his seed, through the law, but through the righteousness of faith. (Romans 4:13) Therefore it is of faith, that it might be by grace, to the end the promise might be sure to all the seed; not to that only which is of the law, but to that also which is of the faith of Abraham; who is the father of us all, (Romans 4:16)

D. God develops this faith in the believer. And Simon Peter answered and said, Thou art the Christ, the Son of the living God. And Jesus answered and said unto him, Blessed art thou, Simon Barjona: for flesh and blood hath not revealed it unto thee, but my Father which is in heaven. (Matthew 16:16-17)

E. The Spirit at work in our hearts is a sign to us of God's interest in us. Now he which stablisheth us with you in Christ, and hath anointed us, is God; Who hath also sealed us, and given the earnest of the Spirit in our hearts. (2 Corinthians 1:21-22)

F. The Holy Spirit uses preaching to cultivate genuine faith. So then faith cometh by hearing, and hearing by the word of God. (Romans 10:17)

G. All these things occur out of sheer grace for the sake of Christ. But God, who is rich in mercy, for his great love wherewith he loved us, Even when we were dead in sins, hath quickened us together with Christ, (by grace ye are saved;) And hath raised us up together, and made us sit together in heavenly places in Christ Jesus: That in the ages to come he might shew the exceeding riches of his grace in his kindness toward us through Christ Jesus. For by grace are ye saved through faith; and that not of yourselves: it is the gift of God. Not of works, lest any man should boast. (Ephesians 2:4-9)

III. The Redeemed Will Believe the Revealed Gospel

A. God gave us the Scriptures so we would know and could then believe the truth. But these are written, that ye might believe that Jesus is the Christ, the Son of God; and that believing ye might have life through his name. (John 20:31)

B. Genuine faith functions through propositions commanded by Jesus. And Jesus came and spake unto them, saying, All power is given unto me in heaven and in earth. Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost. Teaching them to observe all things whatsoever I have commanded you: and, lo, I am with you alway, even unto the end of the world. Amen. (Matthew 28:18-20)

 

C. The Apostles' Creed is the universally acknowledged confession of faith for the Christians.

                              The Apostles' Creed

           I believe in God the Father Almighty,  Maker of heaven and earth;  and in Jesus Christ, His only Son, our Lord: Who was conceived by the Holy Ghost, born of the Virgin Mary, suffered under Pontius Pilate, was crucified, died, and was buried; He descended into hell. the third day He rose again from the dead; He ascended into heaven, and sitteth at the right hand of God the Father Almighty; From thence He shall come to judge the quick and the dead.

I believe in the Holy Ghost; the holy catholic church, the communion of saints; the forgiveness of sins; the resurrection of the body and the life everlasting.  AMEN