Isaiah 6:5 (a) The reference is to the fact that the prophet felt that his words were not what they should be; his messages were not as clear and true as they should be. He felt that from his lips came some things that did not have GOD's approval. He realized that this also was true of the Israelites among whom he dwelt.
Isaiah 64:6 (b) This word reveals our condition before GOD in relationship to Him and others. What we are and what we say very often defiles other people. What we are naturally in our sins prevents us from coming into GOD's holy presence. We defile holy things when we contact them in our natural state.
Haggai 2:13 (b) Our Lord is revealing to us that holiness and godliness cannot be transmitted to another by contact. Sinful things are transmitted to others easily. The saved father and mother do not pass on their godly character in CHRIST to their children, but they certainly do pass on their evils to their children.
Acts 10:28 (a) The "animals" that Peter saw in the sheet represent peoples who had been cleansed by the sacrifice of CHRIST, the Blood had put away their evil, and they were fit for Heaven. The Lord shows them in the sheet as animals because that was our natural state. Now Peter is to be sent to the Gentiles, who were considered only as unclean animals in the sight of the Jews. Peter was being taught that every man is eligible to be made clean by the Gospel of our Lord JESUS CHRIST. None are excluded. (See Acts 11:8). In this passage Peter is referring to foods that GOD permitted to be eaten, and other foods which were prohibited. He was very careful about keeping all the law.
Romans 14:14 (c) In this passage the word seems to be used to indicate our thoughts about various matters in the Christian life. The converted Jew thinks that pork is unclean for him to eat, and he refuses it. The devout Catholic thinks that all meat is unclean on certain occasions. These words indicate the attitude of mind toward certain matters which are given prominence in some religions.
2 Corinthians 6:17 (a) The unclean people here represent all unsaved people of every kind no matter how nice, beautiful or religious. Only those who have been born again, saved by grace, and washed in the Blood of the Lamb, are reckoned as "clean" in GOD's sight. They have been given the gift of righteousness.
Revelation 18:2 (b) Birds in the Scripture are usually connected with Satan and his angels. This Scripture is informing us that the great apostate religions, and evil religious systems of the world are occupied by demons who control the teachings and the practices of those religions.