It is in the Acts of the Apostles, and the Epistles of St. Paul, that we find the details of his life and the system of his doctrine; but, how can we be certain of the authenticity of these works, whilst we see many of the first Christians doubt and reject them as apocryphal? We find, in fact, that from the earliest period of the church, entire sects of Christians, who believed that many of the Epistles published under the name of this Apostle, were not really his. The Marcionites were confident that the gospels were filled with falshoods, and Marcion, their head, pretended that his gospel was the only true one. The Manicheans, who formed a very numerous sect at the commencement of Christianity, rejected as false, all the New Testament, and produced other writings, quite different, which they gave as authentic. The Corinthians, as well as the Marcionites, did not admit the Acts of the Apostles. The Encratites and the Severians did not adopt either the Acts or the Epistles of St. Paul. St. John Chrysostom in a homily, which he has made upon the Acts, says, that in his time (that is to say, towards the end of the fourth century) many men were ignorant not only of the name of the author, or of the collector of these Acts, but even did not know this work. The Valentinians, as well as many other sects of Christians accused our scriptures of being filled with errors, imperfections, and contradictions, and of being insufficient without the assistance of traditions; this is a fact that is attested to us by St. Irenæus. The Ebionites or Nazarenes, who, as we shall soon see, were the first Christians, rejected all the Epistles of St. Paul, and regarded him as an impostor and hypocrite. It will not fail being said to us, that we ought not to rely on the testimony of heretics; but I shall reply, that in the matter in question, their testimony is of the same weight as that of the orthodox, seeing that all the different sects consider themselves as orthodox, and have treated their adversaries as heretics. How shall we unravel the truth if we do not hear both parties? By what signs shall we know those on whom we ought to rely? Shall we cede the cause without examining their adversaries, to writers who utter to us falshoods without number, who contradict each other, who are never agreed amongst themselves, and whose discordant writings are nevertheless produced as proofs of what they advance? In any other subject such a conduct would seem to betray a partiality or even insincerity: but in religious matters, every thing is fair, and there is no necessity of being so nice.