But though we, or an angel from heaven, preach any other gospel unto you than that which we have preached unto you, let him be accursed. As we said before, so say I now again, if any man preach any other gospel unto you than that ye have received, let him be accursed.
You need to familiarize yourself with the New Covenant of gospel of the grace of Christ:
No man is justified by the law (Rom 3:20; Galatians 2:26, 3:11, 5:4).
We are justified ONLY by grace (Rom 3:24; Galatians 5:4; Titus 3:7).
God was in Christ, reconciling the world unto himself, not imputing their trespasses unto them 2 Cor. 5:19.
And he is the propitiation for our sins: and not for ours only, but also for the sins of the whole world 1 John 2:2.
For sin shall not have dominion over you: for you are not under the law, but under grace Romans 6:14.
But now has 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 says, Behold, the days come, says 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, says 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 neighbor, 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 says, A new covenant, he has made the first old. Now that which decays and waxes old is ready to vanish away (Hebrews 8:6-13).