The Old Testament and The New Testament

For someone who is trying to get right with God now, why is it hard for me to convince them that they should start with the book of Matthew? To read the new testament? Not dissuading them from the old testament altogether, but if they are seeking God's grace that they should read the new testament.  Hebrews 8 better explains it Hebrews 8 
8For 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:  
9Not 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.  
10For 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:  
11And 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.

12For I will be merciful to their unrighteousness, and their sins and their iniquities will I remember no more. 13In that he saith, A new covenant, he hath made the first old. Now that which decayeth and waxeth old is ready to vanish away. 


No need to argue among yourselves, just read Hebrews 8. Don't let satan discourage you and say it's too late or that you are not worthy, look how long it took you. God gives us grace through Christ. Don't tempt God (Matthew 4:7) and don't take his grace for granted (Romans 6)