This is continuation of sorts from my previous post on the early church fathers on baptism.
For whatever unbaptized persons die confessing Christ, this confession is of the same efficacy for the remission of sins as if they were washed in the sacred font of baptism. For He who said, “Unless a man be born of water and of the Spirit, he cannot enter into the kingdom of God,”  made also an exception in their favor, in that other sentence where He no less absolutely said, “Whosoever shall confess me before men, him will I confess also before my Father which is in heaven;”  and in another place, “Whosoever will lose his life for my sake, shall find it.”  And this explains the verse, “Precious in the sight of the Lord is the death of His saints.”  For what is more precious than a death by which a man’s sins are all forgiven, and his merits increased an hundredfold? For those who have been baptized when they could no longer escape death, and have departed this life with all their sins blotted out have not equal merit with those who did not defer death, though it was in their power to do so, but preferred to end their life by confessing Christ, rather than by denying Him to secure an opportunity of baptism. And even had they denied Him under pressure of the fear of death, this too would have been forgiven them in that baptism, in which was remitted even the enormous wickedness of those who had slain Christ. But how abundant in these men must have been the grace of the Spirit, who breathes where He lists, seeing that they so dearly loved Christ as to be unable to deny Him even in so sore an emergency, and with so sure a hope of pardon! Precious, therefore, is the death of the saints, to whom the grace of Christ has been applied with such gracious effects, that they do not hesitate to meet death themselves, if so be they might meet Him. And precious is it, also, because it has proved that what was originally ordained for the punishment of the sinner, has been used for the production of a richer harvest of righteousness. But not on this account should we look upon death as a good thing, for it is diverted to such useful purposes, not by any virtue of its own, but by the divine interference. Death was originally proposed as an object of dread, that sin might not be committed; now it must be undergone that sin may not be committed, or, if committed, be remitted, and the award of righteousness bestowed on him whose victory has earned it.
My notes: Clearly Augustine has in view the idea that if one dies because of one’s faith, that is, put to death because one is a Christian, that death acts as a baptism even if one was never baptized according to the traditions of the Church. In other words, one does not need to be baptized, that is immersed (or doused) in water, in order to be saved if one dies for Christ before one can be properly baptized. Martyrdom is a baptism. By implication, then, other than martyrdom one must undergo traditional water baptism in order to be saved. Water baptism seems to be required by the early church on the whole.
Other questions: Does baptism blot out sins? Is martyrdom a guarantee of salvation? How does death increase one’s merits a hundred fold? I need to study Augustine more. I fear I am in far too deep of waters for now.
Finally: What do we do with verses such as Matthew 7:21-23. Christ says: “Not everyone who says to me, ‘Lord, Lord,’ will enter the kingdom of heaven, but the one who does the will of my Father who is in heaven. On that day many will say to me, ‘Lord, Lord, did we not prophesy in your name, and cast out demons in your name, and do many mighty works in your name?’ And then will I declare to them, ‘I never knew you; depart from me, you workers of lawlessness.'” Along with casting out demons and doing mighty works in the name of Christ, could this verse have included “even being put to death in your name?” Presumably, then, one can still be a martyr and not be “known” by Christ. Thus, it would follow, martyrdom does (or might) not overide the true spititual condition of the individual, even if that death is seen as a kind of baptism that comes as a result of “confessing Christ.” Again, I do not know enough of Augustine’s thought to know what was his position on this.
 John 3:5
 Matthew 10:32
 Matthew 16:25
 Psalms 116:15