Mt. 5:17 “Do not think that I have come to abolish the Law or the Prophets; I have not come to abolish them but to fulfill them.
Mt. 5:18 I tell you the truth, until heaven and earth disappear, not the smallest letter, not the least stroke of a pen, will by any means disappear from the Law until everything is accomplished.
Mt. 5:19 Anyone who breaks one of the least of these commandments and teaches others to do the same will be called least in the kingdom of heaven, but whoever practises and teaches these commands will be called great in the kingdom of heaven."

Jesus never established any religion that is different from the religion of the Old Testament. All he did was to show the OT the way God sees it. Or rather, God revealed through Jesus the real meaning of some things in the OT. Through Jesus we learn that the OT commandments are in three categories. The highest category deals with loving the Lord your God. The second category deals with loving your neighbor. The lowest category is loving yourself. Hence, keeping the Sabbath holy is about loving yourself; giving your body some rest in order to avoid breakdown. In a situation where there is conflict between loving God, your neighbor or yourself, loving God must have priority, followed by loving your neighbor. Jesus found himself in such a conflicting situation when he delivered a person from infirmity on a Sabbath day. The Jews opposed him because they did not know that the commandments of God are all about prioritized categories of love.

Another revelation that God gave through Jesus Christ about the OT is the need to rely on the power of God. This is where faith comes in. You cannot see God, neither can you see His power. In order to key in to the power of God, you must come to believe in the invisible God and in the reality of His power and that this power is available to you. Faith is not about having some facts in your head; it is more about acquisition of experience. If you encounter God, you will know that He is real. If you experience His power at work, you immediately develop faith in the power of God.

The only purpose of faith is to enable much work. Faith is all about keying in to the power of God. And the only reason for keying in to power is to do much work. That is why faith without work is useless. Work without faith achieves very little; without faith a person cannot key in to the power of God and so works with human power, which is not much.