Matt 15:10-12
10 And after He called the multitude to Him, He said to them, "Hear, and understand. 11 "Not what enters into the mouth defiles the man, but what proceeds out of the mouth, this defiles the man."
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Mark 7:18-23
18 And He said to them, "Are you so lacking in understanding also? Do you not understand that whatever goes into the man from outside cannot defile him; 19 because it does not go into his heart, but into his stomach, and is eliminated? "(Thus He declared all foods clean.) 20 And He was saying, "That which proceeds out of the man, that is what defiles the man. 21 "For from within, out of the heart of men, proceed the evil thoughts, fornications, thefts, murders, adulteries, 22 deeds of coveting and wickedness, as well as deceit, sensuality, envy, slander, pride and foolishness. 23 "All these evil things proceed from within and defile the man."
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Acts 15:22-29
22 Then it seemed good to the apostles and the elders, with the whole church, to choose men from among them to send to Antioch with Paul and Barnabas-- Judas called Barsabbas, and Silas, leading men among the brethren, 23 and they sent this letter by them,
"The apostles and the brethren who are elders, to the brethren in Antioch and Syria and Cilicia who are from the Gentiles, greetings.
24 "Since we have heard that some of our number to whom we gave no instruction have disturbed you with their words, unsettling your souls, 25 it seemed good to us, having become of one mind, to select men to send to you with our beloved Barnabas and Paul, 26 men who have risked their lives for the name of our Lord Jesus Christ.
27 "Therefore we have sent Judas and Silas, who themselves will also report the same things by word of mouth.
28 "For it seemed good to the Holy Spirit and to us to lay upon you no greater burden than these essentials: 29 that you abstain from things sacrificed to idols and from blood and from things strangled and from fornication; if you keep yourselves free from such things, you will do well. Farewell. "
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Gal 3:23-24
23 But before faith came, we were kept in custody under the law, being shut up to the faith which was later to be revealed. 24 Therefore the Law has become our tutor to lead us to Christ, that we may be justified by faith.
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A little bit of Bible study would answer your questions about the dietary Laws, as well as the other OT Laws.