What kind of religion has worth?
If anyone thinks he is religious and does not bridle his tongue but deceives his heart, this person's religion is worthless. Religion that is pure and undefiled before God, the Father, is this: to visit orphans and widows in their affliction, and to keep oneself unstained from the world. James 1:26-27, ESV
No Christian wants to hear the words "I never knew you; depart from me, you workers of lawlessness." on judgement day. So of course we want to know what we should do 'in his name'; what should our religion should look like?
The Law of Moses
Although the Law looked a lot like 'rule upon rule', even the outward religious rituals were intended to be a pattern for the the overflow of a deeper religion in the heart. Circumcision, that manifestly and inherently external and superficial sign, is the most deliberate example:
“And now, Israel, what does the Lord your God require of you, but to fear the Lord your God, to walk in all his ways, to love him, to serve the Lord your God with all your heart and with all your soul, and to keep the commandments and statutes of the Lord, which I am commanding you today for your good? Behold, to the Lord your God belong heaven and the heaven of heavens, the earth with all that is in it. Yet the Lord set his heart in love on your fathers and chose their offspring after them, you above all peoples, as you are this day. Circumcise therefore the foreskin of your heart, and be no longer stubborn. Deuteronomy 10:12-16, ESV
The Sign without the Heart
Much of the Bible concerns Israel's failure to practice the religion that God wants — and this is all for our benefit, that we should learn from their failure and not make the same mistakes. But what did they do wrong? By the end of the Old Testament, the prophets are shouting it from the rooftops:
“I hate, I despise your feasts, and I take no delight in your solemn assemblies. Even though you offer me your burnt offerings and grain offerings, I will not accept them; and the peace offerings of your fattened animals, I will not look upon them. Take away from me the noise of your songs; to the melody of your harps I will not listen. But let justice roll down like waters, and righteousness like an ever-flowing stream. Amos 5:21-24, ESV
As Israel became more and more religious on the outside, they became more rotten on the inside. To God, this is worse than open disobedience. It is no coincidence at all that Jesus was born into Israel's most 'religious' period:
“Woe to you, scribes and Pharisees, hypocrites! For you are like whitewashed tombs, which outwardly appear beautiful, but within are full of dead people's bones and all uncleanness. So you also outwardly appear righteous to others, but within you are full of hypocrisy and lawlessness. Matthew 23:27-28, ESV
Religion that is pure
So what should our religion look like? What is "Religion that is pure and undefiled before God"? Should we simply "visit orphans and widows in their affliction" as James says? No. James is not revealing a new set of external rules for us. He is choosing examples of outward acts that more obviously reflect the true religion of the heart that pleases God. If we “love your neighbour as yourself”, we "are doing well". Of course this is what all the apostles say, and Jesus said it too. Pure religion is, as it always was, circumcision of the heart, not the foreskin. Although we can't see the heart directly, we can see it's overflow. Worthless religion is easily faked — A regenerate heart is impossible to hide.