In chapter 18 the great principles proper to the new order of things are made known to the disciples. Let us search a little into these sweet and precious instructions of the Lord.
They may be looked at in two ways. They reveal the ways of God with regard to that which was to take the place of the Lord upon earth, as a testimony to grace and truth. Besides this, they depict the character which is in itself the true testimony to be rendered.
This chapter supposes Christ rejected and absent, the glory of chapter 17 not yet come. It passes over chapter 17 to connect itself with chapter 16 (except so far as the last verses of chapter 17 give a practical testimony to His abdication of His true rights until God should vindicate them). The Lord speaks of the two subjects contained in chapter 16, the kingdom and the church.
That which would be proper for the kingdom was the meekness of a little child, which is unable to assert its own rights in the face of a world that passes it by-the spirit of dependence and humility. They must become as little children. In the absence of their rejected Lord this was the spirit that became His followers. He who received a little child in the name of Jesus received Himself. On the other hand, he who put a stumbling-block in the way of one of those little ones who believed in Jesus  should be visited with the most terrible judgment. Alas! the world do this; but woe unto the world on that account. As to the disciples, if that which they most valued became a snare to them, they must pluck it out and cut it off-must exercise the utmost carefulness in grace not to be a snare to a little one believing in Christ, and the most unrelenting severity as to themselves, in whatever might be a snare to them. Loss of what was most precious here was nothing, compared with their eternal condition in another world; for that was in question now, and sin could have no place in God's house. Care for others, even the weakest, severity with self was the rule of the kingdom that no snare or evil might be. As to offence, full grace in forgiveness. They were not to despise these little ones; for if unable to force their own way in this world, they were the objects of the Father's special favour, as those who, in earthly courts, had the peculiar privilege of seeing the king's face. Not that there was no sin in them, but that the Father did not despise those that were far from Him. The Son of man was come to save the lost.  And it was not the Father's will that one of these little ones should perish. He spoke, I doubt not, of little children like those whom He took in His arms; but He inculcates on His disciples the spirit of humility and dependence on the one hand, and on the other, the spirit of the Father, which they were to imitate in order to be truly the children of the kingdom; and not to walk in the spirit of man, who seeks to maintain his place and his own importance, but to humble themselves and submit to contumely; and at the same time (and this is true glory) to imitate the Father, who considers the lowly and admits them into His presence. The Son of man was come on behalf of the worthless. This is the spirit of grace spoken of at the end of chapter 5. It is the spirit of the kingdom.
But the assembly more especially was to occupy the place of Christ on earth. With respect to offences against oneself, this same spirit of meekness became His disciple; he was to gain his brother. If the latter would hearken, the thing was to be buried in the heart of the one whom he had offended; if not, two or three more were then to be taken with him by the offended person to reach his conscience, or serve as witnesses; but if these appointed means were unavailing, it must be made known to the assembly; and if this did not produce submission, he who had done the wrong should be to him as a stranger, as a heathen and a publican was to Israel. The public discipline of the assembly is not treated of here, but the spirit in which Christians were to walk. If the offender bowed when spoken to, even seventy times seven times a day, he was to be forgiven. But though church discipline be not spoken of, we see that the assembly took the place of Israel on earth. The without and within henceforth applied to it. Heaven would ratify that which the assembly bound on earth, and the Father would grant the prayer of two or three who should agree together in making their request; for Christ would be in the midst wherever two or three should be gathered together in or to His name.  Thus, for decisions, for prayers, they were as Christ on the earth, for Christ Himself was there with them. Solemn truth! immense favour, bestowed on two or three when really gathered together in His name; but which forms asubject of the deepest grief when this unity is pretended to, while the reality is not there. 
Another element of the character proper to the kingdom, which had been manifested in God and in Christ, is pardoning grace. In this also the children of the kingdom are to be imitators of God, and always to forgive. This refers only to wrongs done to oneself, and not to public discipline. We must pardon to the end, or rather, there must be no end; even as God has forgiven us all things. At the same time, I believe that the dispensations of God to the Jews are here described. They had not only broken the law, but they had slain the Son of God. Christ interceded for them, saying, "Father, forgive them, for they know not what they do." In answer to this prayer, a provisional pardon was preached by the Holy Ghost, through the mouth of Peter. But this grace too was rejected. When it was a question of shewing grace to the Gentiles, who, no doubt, owed them the hundred pence, they would not hear of it, and they are given up to punishment,  until the Lord can say, "They have received double for all their sins."
In a word, the spirit of the kingdom is not outward power, but lowliness; but in this condition there is nearness to the Father, and then it is easy to be meek and humble in this world. One who has tasted the favour of God will not seek greatness on earth; he is imbued with the spirit of grace, he cherishes the lowly, he pardons those who have wronged him, he is near God, and resembles Him in his ways. The same spirit of grace reigns, whether in the assembly or in its members. It alone represents Christ on the earth; and to it relate those regulations which are founded on the acceptance of a people as belonging unto God. Two or three really gathered together in the name of Jesus act with His authority, and enjoy His privileges with the Father, for Jesus Himself is there in their midst.