What is so interesting about Tertullian's discussion is that it strenuously asserts that Jesus did not introduce a new commandment - but is this true? If we look back at our version of the text:In the true Gospel, a certain doctor of the law comes to the Lord and asks, "What shall I do to inherit eternal life? "In the heretical gospel life only is mentioned, without the attribute eternal; so that the lawyer seems to have consulted Christ simply about the life which the Creator in the law promises to prolong,1030 and the Lord to have therefore answered him according to the law, "Thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy strength," since the question was concerning the conditions of mere life. But the lawyer of course knew very well in what way the life which the law meant was to be obtained, so that his question could have had no relation to the life whose rules he was himself in the habit of teaching. But seeing that even the dead were now raised by Christ, and being himself excited to the hope of an eternal life by these examples of a restored one, he would lose no more time in merely looking on (at the wonderful things which had made him) so high in hope. He therefore consulted him about the attainment of eternal life. Accordingly, the Lord, being Himself the same, and introducing no new precept other than that which relates above all others to (man's) entire salvation, even including the present and the future life,1037 places before him1038 the very essence1039 of the law----that he should in every possible way love the Lord his God. If, indeed, it were only about a lengthened life, such as is at the Creator's disposal, that he inquired and Christ answered, and not about the eternal life, which is at the disposal of Marcion's god, how is he to obtain the eternal one? Surely not in the same manner as the prolonged life. For in proportion to the difference of the reward must be supposed to be also the diversity of the services. Therefore your disciple Marcion, will not obtain his eternal life in consequence of loving your God, in the same way as the man who loves the Creator will secure the lengthened life. But how happens it that, if He is to be loved who promises the prolonged I life, He is not much more to be loved who offers the eternal life? Therefore both one and the other life will be at the disposal of one and the same Lord; because one and the same discipline is to be followed for one and the other life. What the Creator teaches to be loved, that must He necessarily maintain1042 also by Christ,1043 for that rule holds good here, which prescribes that greater things ought to be believed of Him who has first lesser proofs to show, than of him for whom no preceding smaller presumptions have secured a claim to be believed in things of higher import. It matters not then, whether the word eternal has been interpolated by us. It is enough for me, that the Christ who invited men to the eternal----not the lengthened----life, when consulted about the temporal life which he was destroying, did not choose to exhort the man rather to that eternal life which he was introducing. Pray, what would the Creator's Christ have done, if He who had made man for loving the Creator did not belong to the Creator? I suppose He would have said that the Creator was not to be loved!
He answered, “‘Love the Lord your God with all your heart and with all your soul and with all your strength and with all your mind’[a]; and, ‘Love your neighbor as yourself
But Clement, Tertullian and others know of a different version of the last part seemingly cited from Leviticus 19:18 again. As Eric Obsorne right
If we begin from the neighbour we find that he is already identified with Jesus (Clement says elsewhere, 'You have seen your brother, you have seen your God'), and Jesus is identified with god because of his love (p. 149)
εἶδες γάρ τὸν ἀδελφόν σου, εἶδες τὸν θεόν σου
http://books.google.com/books?id=bqRGI6 ... 85&f=false
Even the Marcionite in De Recta in Deum Fide seems to approve of (John 13:34-35), Jesus said, “A new commandment I give to you, that you love one another, even as I have loved you, that you also love one another. By this all men will know that you are My disciples, if you have love for one another.”
This would certainly be the right context for this statement. But is there any evidence for this? Must revisit De Recta in Deum Fide later.