Does Paul's statement in Romans 14:14 Romans 14:14I know, and am persuaded by the Lord Jesus, that there is nothing unclean of itself: but to him that esteems any thing to be unclean, to him it is unclean.
American King James Version×—"I know and am convinced by the Lord Jesus that there is nothing unclean of itself"—mean the early Church made no distinction between clean and unclean meats?

An understanding of Greek terminology can help us here.

It is important to realize that the New Testament writers referred to two concepts of unclean, using different Greek words to convey the two ideas. Unclean could refer to animals God did not intend to be used as food (listed in Leviticus 11 and Deuteronomy 14). Unclean could also refer to ceremonial uncleanness.

In Romans 14 Paul uses the word koinos, which means "common" (W.E. Vine, Vine's Complete Expository Dictionary of Old and New Testament Words, 1985, "Unclean," p. 649). In addition to the meanings of "common" and "ordinary," as used in English (Acts 2:44 Acts 2:44And all that believed were together, and had all things common;
American King James Version×; Acts 4:32 Acts 4:32And the multitude of them that believed were of one heart and of one soul: neither said any of them that ought of the things which he possessed was his own; but they had all things common.
American King James Version×; Titus 1:4 Titus 1:4To Titus, my own son after the common faith: Grace, mercy, and peace, from God the Father and the Lord Jesus Christ our Savior.
American King James Version×; Hebrews 10:29 Hebrews 10:29Of how much sorer punishment, suppose you, shall he be thought worthy, who has trodden under foot the Son of God, and has counted the blood of the covenant, with which he was sanctified, an unholy thing, and has done despite to the Spirit of grace?
American King James Version×; Jude 1:3 Jude 1:3Beloved, when I gave all diligence to write to you of the common salvation, it was needful for me to write to you, and exhort you that you should earnestly contend for the faith which was once delivered to the saints.
American King James Version×), the word also applied to things considered polluted or defiled. This word, along with its verb form koinoo, is used in Mark 7:2-23 Mark 7:2-23 [2] And when they saw some of his disciples eat bread with defiled, that is to say, with unwashed, hands, they found fault. [3] For the Pharisees, and all the Jews, except they wash their hands oft, eat not, holding the tradition of the elders. [4] And when they come from the market, except they wash, they eat not. And many other things there be, which they have received to hold, as the washing of cups, and pots, brazen vessels, and of tables. [5] Then the Pharisees and scribes asked him, Why walk not your disciples according to the tradition of the elders, but eat bread with unwashed hands? [6] He answered and said to them, Well has Esaias prophesied of you hypocrites, as it is written, This people honors me with their lips, but their heart is far from me. [7] However, in vain do they worship me, teaching for doctrines the commandments of men. [8] For laying aside the commandment of God, you hold the tradition of men, as the washing of pots and cups: and many other such like things you do. [9] And he said to them, Full well you reject the commandment of God, that you may keep your own tradition. [10] For Moses said, Honor your father and your mother; and, Whoever curses father or mother, let him die the death: [11] But you say, If a man shall say to his father or mother, It is Corban, that is to say, a gift, by whatever you might be profited by me; he shall be free. [12] And you suffer him no more to do ought for his father or his mother; [13] Making the word of God of none effect through your tradition, which you have delivered: and many such like things do you. [14] And when he had called all the people to him, he said to them, Listen to me every one of you, and understand: [15] There is nothing from without a man, that entering into him can defile him: but the things which come out of him, those are they that defile the man. [16] If any man have ears to hear, let him hear. [17] And when he was entered into the house from the people, his disciples asked him concerning the parable. [18] And he said to them, Are you so without understanding also? Do you not perceive, that whatever thing from without enters into the man, it cannot defile him; [19] Because it enters not into his heart, but into the belly, and goes out into the draught, purging all meats? [20] And he said, That which comes out of the man, that defiles the man. [21] For from within, out of the heart of men, proceed evil thoughts, adulteries, fornications, murders, [22] Thefts, covetousness, wickedness, deceit, lasciviousness, an evil eye, blasphemy, pride, foolishness: [23] All these evil things come from within, and defile the man.
American King James Version×, where it obviously refers to ceremonial uncleanness in the incident when the disciples ate without having first washed their hands.

Through a concordance or similar Bible help you can verify that koinos and koinoo appear throughout the New Testament to refer to this kind of ceremonial uncleanness. Something could be "common"—ceremonially unclean—even though it was otherwise considered a clean meat.

An entirely different word, akathartos, is used in the New Testament for animals Scripture specifies as unclean. In the Septuagint (the Greek translation of the Old Testament in wide use in Paul's day), akathartos is used to designate the unclean meats listed in Leviticus 11 and Deuteronomy 14.

Both words, koinos and akathartos, are used in Acts 10 in describing Peter's vision of the sheet filled with "all kinds of four-footed animals of the earth, wild beasts, creeping things, and birds of the air" (Acts 10:12 Acts 10:12Wherein were all manner of four footed beasts of the earth, and wild beasts, and creeping things, and fowls of the air.
American King James Version×), both clean and unclean. Peter himself distinguished between the two concepts of uncleanness by using both words in Acts 10:14 Acts 10:14But Peter said, Not so, Lord; for I have never eaten any thing that is common or unclean.
American King James Version×. After a voice told Peter to "kill and eat," he replied, "I have never eaten anything common [koinos] or unclean [akathartos]." Most Bible translations distinguish between the meanings of the two words used here. Peter used the same terminology in Acts 10:28 Acts 10:28And he said to them, You know how that it is an unlawful thing for a man that is a Jew to keep company, or come to one of another nation; but God has showed me that I should not call any man common or unclean.
American King James Version×and Acts 11:8 Acts 11:8But I said, Not so, Lord: for nothing common or unclean has at any time entered into my mouth.
American King James Version×in discussing this vision.

When Paul said in Romans 14:14 Romans 14:14I know, and am persuaded by the Lord Jesus, that there is nothing unclean of itself: but to him that esteems any thing to be unclean, to him it is unclean.
American King James Version×that "there is nothing unclean [koinos, or 'common'] of itself," he was making the same point he had made earlier to the Corinthians, as explained in the next chapter of this booklet: Just because meat that was otherwise lawful to eat may have been associated with idol worship does not mean it is intrinsically unfit for human consumption. As seen from the context, Paul wasn't discussing biblical dietary restrictions at all.

Paul goes on to state in Romans 14:20 Romans 14:20For meat destroy not the work of God. All things indeed are pure; but it is evil for that man who eats with offense.
American King James Version×that "all food is clean" (New International Version). The word translated "clean" is katharos, "free from impure admixture, without blemish, spotless" (Vine, "Clean, Cleanness, Cleanse, Cleansing," p. 103). Clean meats as such aren't addressed in the New Testament, so there isn't a specific word to describe them. Katharos is used to describe all kinds of cleanliness and purity, including clean dishes (Matthew 23:26 Matthew 23:26You blind Pharisee, cleanse first that which is within the cup and platter, that the outside of them may be clean also.
American King James Version×), people (John 13:10 John 13:10Jesus said to him, He that is washed needs not save to wash his feet, but is clean every whit: and you are clean, but not all.
American King James Version×) and clothing (Revelation 15:6 Revelation 15:6And the seven angels came out of the temple, having the seven plagues, clothed in pure and white linen, and having their breasts girded with golden girdles.
American King James Version×; Revelation 19:8-14 Revelation 19:8-14 [8] And to her was granted that she should be arrayed in fine linen, clean and white: for the fine linen is the righteousness of saints. [9] And he said to me, Write, Blessed are they which are called to the marriage supper of the Lamb. And he said to me, These are the true sayings of God. [10] And I fell at his feet to worship him. And he said to me, See you do it not: I am your fellow servant, and of your brothers that have the testimony of Jesus: worship God: for the testimony of Jesus is the spirit of prophecy. [11] And I saw heaven opened, and behold a white horse; and he that sat on him was called Faithful and True, and in righteousness he does judge and make war. [12] His eyes were as a flame of fire, and on his head were many crowns; and he had a name written, that no man knew, but he himself. [13] And he was clothed with a clothing dipped in blood: and his name is called The Word of God. [14] And the armies which were in heaven followed him on white horses, clothed in fine linen, white and clean.
American King James Version×), "pure" religion (James 1:27 James 1:27Pure religion and undefiled before God and the Father is this, To visit the fatherless and widows in their affliction, and to keep himself unspotted from the world.
American King James Version×), gold and glass (Revelation 21:18 Revelation 21:18And the building of the wall of it was of jasper: and the city was pure gold, like to clear glass.
American King James Version×).

Realize also that, in both Romans 14:14 Romans 14:14I know, and am persuaded by the Lord Jesus, that there is nothing unclean of itself: but to him that esteems any thing to be unclean, to him it is unclean.
American King James Version×and Romans 14:20 Romans 14:20For meat destroy not the work of God. All things indeed are pure; but it is evil for that man who eats with offense.
American King James Version×, the word food or meat isn't in the original wording. No specific object is mentioned relative to cleanness or uncleanness. The sense of these verses is merely that "nothing [is] unclean [koinos: common or ceremonially defiled] of itself," and "all is clean [katharos: free from impure admixture, without blemish, spotless]."

Paul's point is that the possible association of a particular food with idolatrous activity had no bearing on whether the food was suitable for eating.