Why do so many 'Christians' ignore Matthew 23?

¹And the LORD said unto Moses, Hew thee two tables of stone like unto the first: and I will write upon these tables the words that were in the first tables, which thou brakest. ²And be ready in the morning, and come up in the morning unto mount Sinai, and present thyself there to me in the top of the mount. ³And no man shall come up with thee, neither let any man be seen throughout all the mount; neither let the flocks nor herds feed before that mount. ⁴And he hewed two tables of stone like unto the first; and Moses rose up early in the morning, and went up unto mount Sinai, as the LORD had commanded him, and took in his hand the two tables of stone.

⁵And the LORD descended in the cloud, and stood with him there, and proclaimed the name of the LORD. ⁶And the LORD passed by before him, and proclaimed, The LORD, The LORD God, merciful and gracious, longsuffering, and abundant in goodness and truth, ⁷Keeping mercy for thousands, forgiving iniquity and transgression and sin, and that will by no means clear the guilty; visiting the iniquity of the fathers upon the children, and upon the children's children, unto the third and to the fourth generation.

⁸And Moses made haste, and bowed his head toward the earth, and worshipped. ⁹And he said, If now I have found grace in thy sight, O LORD, let my LORD, I pray thee, go among us; for it is a stiffnecked people; and pardon our iniquity and our sin, and take us for thine inheritance. ¹⁰And he said, Behold, I make a covenant: before all thy people I will do marvels, such as have not been done in all the earth, nor in any nation: and all the people among which thou art shall see the work of the LORD: for it is a terrible thing that I will do with thee.

¹¹Observe thou that which I command thee this day: behold, I drive out before thee the Amorite, and the Canaanite, and the Hittite, and the Perizzite, and the Hivite, and the Jebusite. ¹²Take heed to thyself, lest thou make a covenant with the inhabitants of the land whither thou goest, lest it be for a snare in the midst of thee: ¹³But ye shall destroy their altars, break their images, and cut down their groves: 

1)¹⁴For thou shalt worship no other god: for the LORD, whose name is Jealous, is a jealous God: 

¹⁵Lest thou make a covenant with the inhabitants of the land, and they go a whoring after their gods, and do sacrifice unto their gods, and one call thee, and thou eat of his sacrifice; ¹⁶And thou take of their daughters unto thy sons, and their daughters go a whoring after their gods, and make thy sons go a whoring after their gods.

2) ¹⁷Thou shalt make thee no molten gods.

3) ¹⁸The feast of unleavened bread shalt thou keep. Seven days thou shalt eat unleavened bread, as I commanded thee, in the time of the month Abib: for in the month Abib thou camest out from Egypt.

4) ¹⁹All that openeth the matrix is mine; and every firstling among thy cattle, whether ox or sheep, that is male. ²⁰But the firstling of an ass thou shalt redeem with a lamb: and if thou redeem him not, then shalt thou break his neck. All the firstborn of thy sons thou shalt redeem. And none shall appear before me empty.

5) ²¹Six days thou shalt work, but on the seventh day thou shalt rest: in earing time and in harvest thou shalt rest.

6) ²²And thou shalt observe the feast of weeks, of the firstfruits of wheat harvest, and the feast of ingathering at the year's end.

7) ²³Thrice in the year shall all your menchildren appear before the LORD God, the God of Israel. ²⁴For I will cast out the nations before thee, and enlarge thy borders: neither shall any man desire thy land, when thou shalt go up to appear before the LORD thy God thrice in the year.
 
8)²⁵Thou shalt not offer the blood of my sacrifice with leaven; neither shall the sacrifice of the feast of the passover be left unto the morning.

9) ²⁶The first of the firstfruits of thy land thou shalt bring unto the house of the LORD thy God.

10) Thou shalt not seethe a kid in his mother's milk.

²⁷And the LORD said unto Moses, Write thou these words: for after the tenor of these words I have made a covenant with thee and with Israel. ²⁸And he was there with the LORD forty days and forty nights; he did neither eat bread, nor drink water. And he wrote upon the tables the words of the covenant, the ten commandments.