No. You're not comapring apples with apples. Paul has this to say, directly related to Jesus' words about branches grafted in,
"If some of the branches have been broken off, and you, though a wild olive shoot, have been grafted in among the others and now share in the nourishing sap from the olive root, do not consider yourself to be superior to those other branches. If you do, consider this: You do not support the root, but the root supports you. You will say then, “Branches were broken off so that I could be grafted in.” Granted. But they were broken off because of unbelief, and you stand by faith. Do not be arrogant, but tremble. For if God did not spare the natural branches, he will not spare you either." Rom 11:17-21
Your's is a novel argument devised to support a novel gospel a few centuries past..
Of course not. Neither are Jesus and James et al in tension with John and Paul, But none say that man can't resist grace, that believers are necessarily guaranteed to do good works- just the opposite, in fact. We're warned in Rom 6 that sin leads to death and that we must "offer every part of yourself to Him as an instrument of righteousness", because holiness results in eternal life. So Jesus can rightly say,
"If you want to enter life, keep the commandments.” Matt 19:1
“‘Love the Lord your God with all your heart and with all your soul and with all your mind.’ This is the first and greatest commandment. And the second is like it: ‘Love your neighbor as yourself.’ All the Law and the Prophets hang on these two commandments.” Matt 22:36-40
With Paul echoing:
"Let no debt remain outstanding, except the continuing debt to love one another, for whoever loves others has fulfilled the law. The commandments, “You shall not commit adultery,” “You shall not murder,” “You shall not steal,” “You shall not covet,” and whatever other command there may be, are summed up in this one command: “Love your neighbor as yourself.” Love does no harm to a neighbor. Therefore love is the fulfillment of the law." Rom 13:8-10
"To those who by persistence in doing good seek glory, honor and immortality, he will give eternal life." Rom 2:7
"For it is not those who hear the law who are righteous in God’s sight, but it is those who obey the law who will be declared righteous." Rom 2:13
"Therefore, brothers and sisters, we have an obligation—but it is not to the flesh, to live according to it. For if you live according to the flesh, you will die; but if by the Spirit you put to death the misdeeds of the body, you will live. For those who are led by the Spirit of God are the children of God." Rom 8:12-14
"He has made us competent as ministers of a new covenant—not of the letter but of the Spirit; for the letter kills, but the Spirit gives life." 2 Cor 3:6