Children of Yahweh are to separate themselves from the customs and practices of the heathen. It is an abomination to Yahweh to presume to offer worship to Him combined with any of the ways that the heathen worship their gods.
Gen. 35:2 - Then Jacob said unto his household, and to all that were with him, Put away the strange gods that are among you, and be clean, and change your garments.
Exo. 20:3 - Thou shalt have no other gods before me.
Exo. 32:5-10 (A sobering example of how Yahweh feels about mixing in pagan worship and feasts with His worship. See 1 Cor. 10:5-7 below) - And when Aaron saw [the golden calf], he built an altar before it; and Aaron made proclamation, and said, To morrow is a feast to the LORD. 6And they rose up early on the morrow, and offered burnt offerings, and brought peace offerings; and the people sat down to eat and to drink, and rose up to play. 7And the LORD said unto Moses, Go, get thee down; for thy people, which thou broughtest out of the land of Egypt, have corrupted themselves: 8They have turned aside quickly out of the way which I commanded them: they have made them a molten calf, and have worshipped it, and have sacrificed thereunto, and said, These be thy gods, O Israel, which have brought thee up out of the land of Egypt. 9And the LORD said unto Moses, I have seen this people, and, behold, it is a stiffnecked people: 10Now therefore let me alone, that my wrath may wax hot against them, and that I may consume them. (The consequences of this mixing on Israel were very terrible.)
Deut. 7:2-5 -And when the LORD thy God shall deliver them before thee; thou shalt smite them, and utterly destroy them; thou shalt make no covenant with them, nor shew mercy unto them: 3Neither shalt thou make marriages with them; thy daughter thou shalt not give unto his son, nor his daughter shalt thou take unto thy son. 4For they will turn away thy son from following me, that they may serve other gods: so will the anger of the LORD be kindled against you, and destroy thee suddenly. 5But thus shall ye deal with them; ye shall destroy their altars, and break down their images, and cut down their groves, and burn their graven images with fire.
Deut. 12:29-32 -When the LORD thy God shall cut off the nations from before thee, whither thou goest to possess them, and thou succeedest them, and dwellest in their land; 30 Take heed to thyself that thou be not snared by following them, after that they be destroyed from before thee; and that thou enquire not after their gods, saying, How did these nations serve their gods? even so will I do likewise. 31 Thou shalt not do so unto the LORD thy God: for every abomination to the LORD, which he hateth, have they done unto their gods; for even their sons and their daughters they have burnt in the fire to their gods. 32 What thing soever I command you, observe to do it: thou shalt not add thereto, nor diminish from it.
1 Sam. 7:3 - And Samuel spake unto all the house of Israel, saying, If ye do return unto the LORD with all your hearts, then put away the strange gods and Ashtaroth from among you, and prepare your hearts unto the LORD, and serve him only: and he will deliver you out of the hand of the Philistines
2 Chron. 33:6 -And he caused his children to pass through the fire in the valley of the son of Hinnom: also he observed times, and used enchantments, and used witchcraft, and dealt with a familiar spirit, and with wizards: he wrought much evil in the sight of the LORD, to provoke him to anger.
Jer. 10:2-4 -Thus saith the LORD, Learn not the way of the heathen, and be not dismayed at the signs of heaven; for the heathen are dismayed at them. 3For the customs of the people are vain: for one cutteth a tree out of the forest, the work of the hands of the workman, with the axe. 4They deck it with silver and with gold; they fasten it with nails and with hammers, that it move not.
Ezek. 44:23 -And they shall teach my people the difference between the holy and profane, and cause them to discern between the unclean and the clean.
Matt.16:12 - Then understood they how that he bade them not beware of the leaven of bread, but of the doctrine of the Pharisees and of the Sadducees.
Mark 7:6-7 - He answered and said unto them, Well hath Esaias prophesied of you hypocrites, as it is written, This people honoureth me with their lips, but their heart is far from me. 7Howbeit in vain do they worship me, teaching for doctrines the commandments of men.
John 4:23-24 - But the hour cometh, and now is, when the true worshippers shall worship the Father in spirit and in truth: for the Father seeketh such to worship him. 24God is a Spirit: and they that worship him must worship him in spirit and in truth.
1 Cor. 5:6-8 - Know ye not that a little leaven leaveneth the whole lump? 7Purge out therefore the old leaven, that ye may be a new lump, as ye are unleavened. For even Christ our passover is sacrificed for us: 8Therefore let us keep the feast, not with old leaven, neither with the leaven of malice and wickedness; but with the unleavened bread of sincerity and truth.
1 Cor. 10:5-7 - But with many of them God was not well pleased: for they were overthrown in the wilderness. 6Now these things were our examples, to the intent we should not lust after evil things, as they also lusted. 7Neither be ye idolaters, as were some of them; as it is written, The people sat down to eat and drink, and rose up to play.
James 1:27 - Pure 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.
1 John 5:21 - Little children, keep yourselves from idols. Amen.
Rev. 20:4 - And I saw thrones, and they sat upon them, and judgment was given unto them: and I saw the souls of them that were beheaded for the witness of Jesus, and for the word of God, and which had not worshipped the beast, neither his image, neither had received his mark upon their foreheads, or in their hands; and they lived and reigned with Christ a thousand years.
The forehead is marked when false doctrine is believed; the hands are marked when they dabble in and support the false customs and traditions of the Apostacy. We cannot touch or support these false ways, they are unclean and unholy.
Psa. 24:3 - Who shall ascend into the hill of the LORD? or who shall stand in his holy place? 4He that hath clean hands, and a pure heart; who hath not lifted up his soul unto vanity, nor sworn deceitfully. 5He shall receive the blessing from the LORD, and righteousness from the God of his salvation.
Rev. 22:18-19 - For I testify unto every man that heareth the words of the prophecy of this book, If any man shall add unto these things, God shall add unto him the plagues that are written in this book: 19And if any man shall take away from the words of the book of this prophecy, God shall take away his part out of the book of life, and out of the holy city, and from the things which are written in this book.