Refuting Legalistic Covenant Mixing Believers

What do you say to modern day believers that also believe that because God told the Hebrews in the Old Covenant to not eat pork for example or shellfish that we are not supposed to either?  Can they be reasoned with or do we just let them continue and allow the Holy Spirit to work in their lives?

I believe we give the truth where we can but as Romans 14 describes if someone thinks they should not do something because it would be a sin to them then it is sin.  So it seems we correct where we can in love but not at the expense of causing a division.  If you don't want to eat pork because of what Leviticus has to say about pork and shellfish then I'm not going to argue with you.  But the word of God does shed much light on this matter and if you understand this it helps to understand what the New Covenant really is and how people were always saved by faith not works.

All animals created by God are good and considered clean for eating now. 

1 Timothy 4:4 KJV
For every creature of God is good, and nothing to be refused, if it be received with thanksgiving:

If you think something is wrong then if you do it that thing is considered sin even if God allows it. 

Romans 14:14-23 KJV

But if thy brother be grieved with thy meat, now walkest thou not charitably. Destroy not him with thy meat, for whom Christ died.
Let not then your good be evil spoken of:
For the kingdom of God is not meat and drink; but righteousness, and peace, and joy in the Holy Ghost.
For he that in these things serveth Christ is acceptable to God, and approved of men.
Let us therefore follow after the things which make for peace, and things wherewith one may edify another.
For meat destroy not the work of God. All things indeed are pure; but it is evil for that man who eateth with offence.
It is good neither to eat flesh, nor to drink wine, nor any thing whereby thy brother stumbleth, or is offended, or is made weak.
Hast thou faith? have it to thyself before God. Happy is he that condemneth not himself in that thing which he alloweth.
And he that doubteth is damned if he eat, because he eateth not of faith: for whatsoever is not of faith is sin.

And in a vision God told Peter that all things are clean and in the vision told him to kill and eat the meat.

Acts 10:9-16 KJV
On the morrow, as they went on their journey, and drew nigh unto the city, Peter went up upon the housetop to pray about the sixth hour:
And he became very hungry, and would have eaten: but while they made ready, he fell into a trance,
And saw heaven opened, and a certain vessel descending unto him, as it had been a great sheet knit at the four corners, and let down to the earth:
Wherein were all manner of fourfooted beasts of the earth, and wild beasts, and creeping things, and fowls of the air.
And there came a voice to him, Rise, Peter; kill, and eat.
But Peter said, Not so, Lord; for I have never eaten any thing that is common or unclean.
And the voice spake unto him again the second time, What God hath cleansed, that call not thou common.
This was done thrice: and the vessel was received up again into heaven.

And for those that still think we need to keep the Mosaic Law, Paul wrote many letters to Jewish converted believers in Jesus:

This one from Hebrews (Paul may have written Hebrews but that is debated) indicates that the Levitical Priesthood is abolished and JESUS is now our high priest and mediator between God the Father and man.

Hebrews 8:1-13 KJV
Now of the things which we have spoken this is the sum: We have such an high priest, who is set on the right hand of the throne of the Majesty in the heavens;
A minister of the sanctuary, and of the true tabernacle, which the Lord pitched, and not man.
For every high priest is ordained to offer gifts and sacrifices: wherefore it is of necessity that this man have somewhat also to offer.
For if he were on earth, he should not be a priest, seeing that there are priests that offer gifts according to the law:
Who serve unto the example and shadow of heavenly things, as Moses was admonished of God when he was about to make the tabernacle: for, See, saith he, that thou make all things according to the pattern shewed to thee in the mount.
But now hath he obtained a more excellent ministry, by how much also he is the mediator of a better covenant, which was established upon better promises.
For if that first covenant had been faultless, then should no place have been sought for the second.
For finding fault with them, he saith, Behold, the days come, saith the Lord, when I will make a new covenant with the house of Israel and with the house of Judah:
Not according to the covenant that I made with their fathers in the day when I took them by the hand to lead them out of the land of Egypt; because they continued not in my covenant, and I regarded them not, saith the Lord.
For this is the covenant that I will make with the house of Israel after those days, saith the Lord; I will put my laws into their mind, and write them in their hearts: and I will be to them a God, and they shall be to me a people:
And they shall not teach every man his neighbour, and every man his brother, saying, Know the Lord: for all shall know me, from the least to the greatest.
For I will be merciful to their unrighteousness, and their sins and their iniquities will I remember no more.
In that he saith, A new covenant, he hath made the first old. Now that which decayeth and waxeth old is ready to vanish away.

Final Thought:

We must use the word of God to sift through the confusion people have over legalistic Old Covenant rule keeping. It clouds what the gospel is and confuses the Old Covenant and New Covenants by mixing them. Also, if a person doesn’t believe the bible is accurate and true then none of these things matter whatsoever. But if one does consider the bible without error as it was originally delivered then they will study the word to see if those things they hear and are told are true.  This is an honorable thing to do and few will search out a thing to see if it is true as the Bereans did..

Acts 17:10-11 KJV

And the brethren immediately sent away Paul and Silas by night unto Berea: who coming thither went into the synagogue of the Jews.

These were more noble than those in Thessalonica, in that they received the word with all readiness of mind, and searched the scriptures daily, whether those things were so.