Is James teaching against obedience?

For whoever shall keep the whole law, and yet stumble in one point,  he is guilty of all.
James 2:10 NKJV

Is James trying to say, "if you violate one Law, you violate it all, so don't even try to fulfill the Law, you have Jesus!!!"

No... James is talking about Partiality against the poor in favour of the rich. It is based on this pretext that led him to talk about "Faith without works is dead". Here are some of the highlights.

The brethrens showing partiality.

My brethren, do not hold the faith of our Lord Jesus Christ, the  Lord of glory, with PARTIALITY. For if there should come into your assembly a man with gold rings, in fine apparel, and there should also come in a poor man in filthy clothes, and you pay attention to the one wearing the fine clothes and say to him, “You sit here in a good place,” and say to the poor man, “You stand there,” or, “Sit here at my footstool,” have you not shown partiality among yourselves, and become judges with evil thoughts?
James 2:1‭-‬4 NKJV

James rebuke for siding with the rich.

Listen, my beloved brethren: Has God not chosen the poor of this world to  be  rich in faith and heirs of the kingdom which He promised to those who love Him? But you have dishonored the poor man. Do not the rich oppress you and drag you into the courts? Do they not blaspheme that noble name by which you are called?
James 2:5‭-‬7 NKJV

Judgement for showing Partiality, lack of Mercy.

If you really fulfill the royal law according to the Scripture, “You shall love your neighbor as yourself,” you do well; but if you show partiality, you commit sin, and are convicted by the law as transgressors. For whoever shall keep the whole law, and yet stumble in one point,  he is guilty of all. For He who said, “Do not commit adultery,” also said, “Do not murder.” Now if you do not commit adultery, but you do murder, you have become a transgressor of the law. So speak and so do as those who will be judged by the law of liberty. For judgment is without mercy to the one who has shown no mercy. Mercy triumphs over judgment.
James 2:8‭-‬13 NKJV

No point praying for the poor when there is no action done.

What does  it profit, my brethren, if someone says he has faith but does not have works? Can faith save him? If a brother or sister is naked and destitute of daily food, and one of you says to them, “Depart in peace, be warmed and filled,” but you do not give them the things which are needed for the body, what does  it profit? Thus also faith by itself, if it does not have works, is dead.
James 2:14‭-‬17 NKJV

Examples of Justification (of Faith)  by works.

But someone will say, “You have faith, and I have works.” Show me your faith without your works, and I will show you my faith by my works. You believe that there is one God. You do well. Even the demons believe—and tremble! But do you want to know, O foolish man, that faith without works is dead? Was not Abraham our father justified by works when he offered Isaac his son on the altar? Do you see that faith was working together with his works, and by works faith was made perfect? And the Scripture was fulfilled which says, “Abraham believed God, and it was accounted to him for righteousness.” And he was called the friend of God. You see then that a man is justified by works, and not by faith only. Likewise, was not Rahab the harlot also justified by works when she received the messengers and sent them out another way? For as the body without the spirit is dead, so faith without works is dead also.
James 2:18‭-‬26 NKJV

Link this to Chapter 1.

Therefore lay aside all filthiness and overflow of wickedness, and receive with meekness the implanted word, which is able to save your souls. But be doers of the word, and not hearers only, deceiving yourselves. For if anyone is a hearer of the word and not a doer, he is like a man observing his natural face in a mirror; for he observes himself, goes away, and immediately forgets what kind of man he was. But he who looks into the perfect law of liberty and continues in  it, and is not a forgetful hearer but a doer of the work, this one will be blessed in what he does. If anyone among you thinks he is religious, and does not bridle his tongue but deceives his own heart, this one’s religion is useless. Pure and undefiled religion before God and the Father is this: to visit orphans and widows in their trouble, and to keep oneself unspotted from the world.
James 1:21‭-‬27 NKJV

信耶稣得水牛

This is an analogy for a Christmas message I heard from Pastor Jason Lim from Gospel Light Christian Church on Christmas 2016. Just to paraphrase:

There is a church in a small village in China with a relatively small population of Christians. One particular Sunday, they noticed that their attendance exponentially rose. So the Pastor decided to investigate and surveyed the new found believers. When he asked them what had attracted them to come to this church, they told him, "Well, it was promised to us that if we believe in Jesus, we will get a water buffalo (水牛)。".

Perplexed by this, he continued to probe deeper who has given them such a ridiculous promise. The new believers pointed him to a banner that hangs outside of the church door, and it reads, "信耶稣得水牛".

After examining the banner, now he know what is the root of the problem. The words on the banner are actually stuck to the canvas using coloured cardboard paper. During a torrential rain, some of the Strokes of the Chinese Characters fell off. The banner actually reads, "信耶稣得永生". 2 strokes fell off from the Characters "永生" (Eternal Life) and became "水牛" (Water Buffalo).

The new believers based their faith on a promise that if they believe in Jesus, they will get a water buffalo. The water buffalo represents our felt needs, material wants and personal ambitions. Many churches are actually (without realizing), teaching 信耶稣得水牛， instead of 信耶稣得永生。

Is the sinner's Prayer a Passport to heaven?

The problem is, we have been taught that we get a passport to heaven the moment we say the Sinner's Prayer, and then we talk about life transformation or sanctification later. However, Justification by faith is meant for those who wants to follow God but unable to do so perfectly.

So in the first place, a Christian is a sinner who wants to follow God but is unable to do so and therefore needs a saviour... NOT a sinner who merely wants to escape hell and go to heaven.

The Sinner's prayer is an acceptance of Jesus as Lord and Savior. It is not an assurance of Salvation. Salvation is evidenced by true repentance from our former lives, and obedience to our new lives as believers.

3 Now by this we know that we know Him, if we keep His commandments. 4 He who says, “I know Him,” and does not keep His commandments, is a liar, and the truth is not in him. 5 But whoever keeps His word, truly the love of God is perfected in him. By this we know that we are in Him. 6 He who says he abides in Him ought himself also to walk just as He walked. 7 Brethren,[a] I write no new commandment to you, but an old commandment which you have had from the beginning. The old commandment is the word which you heard from the beginning.[b]8 Again, a new commandment I write to you, which thing is true in Him and in you, because the darkness is passing away, and the true light is already shining. 9 He who says he is in the light, and hates his brother, is in darkness until now. 10 He who loves his brother abides in the light, and there is no cause for stumbling in him. 11 But he who hates his brother is in darkness and walks in darkness, and does not know where he is going, because the darkness has blinded his eyes. - 1 John 2:3-11

4 Whoever commits sin also commits lawlessness, and sin is lawlessness. 5 And you know that He was manifested to take away our sins, and in Him there is no sin. 6 Whoever abides in Him does not sin. Whoever sins has neither seen Him nor known Him. 7 Little children, let no one deceive you. He who practices righteousness is righteous, just as He is righteous. 8 He who sins is of the devil, for the devil has sinned from the beginning. For this purpose the Son of God was manifested, that He might destroy the works of the devil. 9 Whoever has been born of God does not sin, for His seed remains in him; and he cannot sin, because he has been born of God. - 1 John 3:4-9

Whoever believes that Jesus is the Christ is born of God, and everyone who loves Him who begot also loves him who is begotten of Him. 2 By this we know that we love the children of God, when we love God and keep His commandments. 3 For this is the love of God, that we keep His commandments. And His commandments are not burdensome. 4 For whatever is born of God overcomes the world. And this is the victory that has overcome the world—our[a] faith. 5 Who is he who overcomes the world, but he who believes that Jesus is the Son of God? - 1 John 5:1-5

2 But we know that the judgment of God is according to truth against those who practice such things. 3 And do you think this, O man, you who judge those practicing such things, and doing the same, that you will escape the judgment of God? 4 Or do you despise the riches of His goodness, forbearance, and longsuffering, not knowing that the goodness of God leads you to repentance? 5 But in accordance with your hardness and your impenitent heart you are treasuring up for yourself wrath in the day of wrath and revelation of the righteous judgment of God, 6 who “will render to each one according to his deeds”:[a] 7 eternal life to those who by patient continuance in doing good seek for glory, honor, and immortality; 8 but to those who are self-seeking and do not obey the truth, but obey unrighteousness—indignation and wrath, 9 tribulation and anguish, on every soul of man who does evil, of the Jew first and also of the Greek; 10 but glory, honor, and peace to everyone who works what is good, to the Jew first and also to the Greek. 11 For there is no partiality with God. - Rom 2:2-11

We don't need to keep reminding people how to live for God. We need to remind people what Salvation means in the first place....