The obligation of the Church is that the Church, as in the Bride of Christ, has a duty to seek justice and strive to provide mercy for the least of these. Because this a Gospel issue, whatever we are doing in genuinely building the kingdom feeds into fighting injustice. However, this does not mean that we do not need to focus efforts on specific injustices (such as abortion or criminal justice reform).

Fighting for justice seems like an obvious thing for Christians. However, there are also many that will preach and teach that it is not the obligation of the believer to seek justice. Instead, these so-called teachers will spend their days thinking up endless different flowery ways of articulating the same points of Calvinism over and over again. Good points, we assure you, but we are called to more than articulating and thinking upon ideas.

What does scripture say about injustice and the duty of the faithful?

'"Woe to you, scribes and Pharisees, hypocrites! For you tithe mint and dill and cummin, and have neglected the weightier provisions of the law: justice and mercy and faithfulness; but these are the things you should have done without neglecting the others.”
Matthew 23:23

“The King will answer and say to them, 'Truly I say to you, to the extent that you did it to one of these brothers of Mine, even the least of them, you did it to Me.' "Then the King will say to those on His right, 'Come, you who are blessed of My Father, inherit the kingdom prepared for you from the foundation of the world. For I was hungry, and you gave Me something to eat; I was thirsty, and you gave Me something to drink; I was a stranger, and you invited Me in; naked, and you clothed Me; I was sick, and you visited Me; I was in prison, and you came to Me.' Then the righteous will answer Him, 'Lord, when did we see You hungry, and feed You, or thirsty, and give You something to drink? And when did we see You a stranger, and invite You in, or naked, and clothe You? When did we see You sick, or in prison, and come to You?'“
Matthew 25:34-40

“Pure and undefiled religion in the sight of our God and Father is this: to visit orphans and widows in their distress, and to keep oneself unstained by the world.”
James 1:27

That is but a tiny sampling and only from the New Testament. Like all of the five tenets, there is plenty to write on that could fill many articles. God demands justice, and without that justice, he hates our worship. What does our church history and traditions teach about our duty to pursue justice?

An excerpt from answer 145 of the Westminster Larger Catechism on bearing false witness shows that the duty of Christians extends beyond merely not telling lies.

“concealing the truth, undue silence in a just cause, and holding our peace when iniquity calleth for either a reproof from ourselves, or complaint to others”

The Westminster authors saw “undue silence in a just cause” as sin; not only caring about our own personal sins but also speaking out for just causes is a duty of the individual Christian. This means that Christians do not only have a negative command to not give false witness, but they also have a positive command to speak on behalf of a just cause.

“Thou shalt not kill” is the summary, heart, and surface of the Sixth Commandment. As nearly every Reformer, notable theologian, and orthodox commentator has noted, the negative command “thou shalt not kill” is paired with a positive command to seek out justice for those oppressed and to interpose on behalf of those being murdered and trampled upon. The heart of the Sixth Commandment, as made evident by our Lord in Matt 5:21-22, is not hating your brother, and inversely, loving your brother.

The duty of all men before God is broader than merely watching out for ourselves. While writing on the Sixth Commandment in his Institutes of the Christian Religion, John Calvin states,

“To be clear of the crime of murder, it is not enough to refrain from shedding man’s blood. If in act you perpetrate, if in endeavour you plot, if in wish and design you conceive what is adverse to another’s safety, you have the guilt of murder. On the other hand, if you do not according to your means and opportunity study to defend his safety, by that inhumanity you violate the law. But if the safety of the body is so carefully provided for, we may hence infer how much care and exertion is due to the safety of the soul, which is of immeasurably higher value in the sight of God.”

John Calvin equates being apathetic about murder with murder itself and then he connects the lack of care for the physical body to a lack of concern for the soul. Calvin does not pit the body against the soul. Yes, he does rightly account the soul as having great value, but he also connects the care for the body to how we care for the soul. In other words, if you do not care for the body, how are we to care for the soul? Those who pit the body against the soul as opposed to seeing its natural union are thinking dualistically and irrationally.

The missionary Amy Carmichael put it this way:

“One can’t save and then pitchfork souls into heaven…Souls are more or less securely fastened to bodies… And as you can’t get the souls out and deal with them separately, you have to take them both together.”

John Calvin saw both a positive and negative aspect to the Law of God. We are not to transgress the plain Law, but we also have duties. To hate your brother is to murder him in your heart. Likewise, to know that your brother is being murdered and to do nothing is to murder your brother in your heart.

Another point to be made regarding Calvin's quote is his qualifier “according to your means and opportunity.” Not everyone is going to have the same ability to stand outside an abortion clinic every day or dedicate years to fighting legislative battles to pass bills of abolition. But we do have means, and we do have the opportunity. Can any of us honestly say that any Christian has no means and no opportunity to speak out against injustice? With our wealth of resources, wealth of disposable time, and our proximity to the horror of abortion, we are confident that we, with the very rare exception, have a great deal of opportunity and many different means to seek justice and expose evil. These means may be varied according to our income, time, location, and giftings, but we have the ability.