The principle to keep in mind is that we have to change ourselves first. 

1. Participate in the Lord’s Supper Every Sunday in Worship
The Kingdom is again and again a feast. The Church is the beachhead of the Kingdom. Does Jesus ever tell a parable comparing the Kingdom to a lecture hall? Does he ever compare the Kingdom to a music concert? Then lets not stop up the Kingdom at the source. Lets get it right. Lets eat and drink.

2. Drink Wine in Church
Duh. How else would you worship a glutton and a drunkard? The Gospel is New Wine that bursts wineskins–not grape juice that sits there inert. You want to know if God can forgive a sinner like you. Get it in a cup and drink it down and you will know. That changes everything.

3. Sing the Psalms
By sing, I mean chant. Don’t remake the Psalms to fit a rhyme scheme. Sing the words that are there according to an accurate translation. What would happen if we did this? For one thing a ton of bad theology would be exorcised.

Arise, O Yahweh
O God, lift up your hand;
forget not the afflicted.
Why does the wicked renounce God
and say in his heart, “You will not call to account”?
But you do see,
for you note mischief and vexation,
that you may take it into your hands;
to you the helpless commits himself;
you have been the helper of the fatherless.
Break the arm of the wicked and evildoer;
call his wickedness to account till you find none.
Yahweh is king forever and ever; the nations perish from his land.

4. Pray the Psalms
Arguably this is redundant with the point above. But I want to stress that God wants us to pray things like:

judge me, O Lord, according to my righteousness
and according to the integrity that is in me.
Oh, let the evil of the wicked come to an end,
and may you establish the righteous—
you who test the minds and hearts,
O righteous God!

There are people and whole churches who claim to be Bible-believing who think this is sinful to pray. You can’t change the world for God if you think He is really a Pharisee unless he has the help of your styleguide by which to edit his prayers.

5. Tell people in church that God has forgiven them.

Don’t preach that God forgives some people somewhere some time. Tell the professing Christians in front of you, and their children, when they confess their sins together, that God has wiped each one of their slates clean. The good news that is going to change the world is not that God forgives someone somewhere at some time.

(Yes, God forgives them at other times, including when they pray apart. But these things are not opposed. Rather, one helps the the other. Those who are trained to believe that God hears and forgives them will be encouraged to trust God for the same at other times and places.)

6. Believe the whole Bible and teach it like God really meant it.

Because saying, “You’re getting too much of your theology from the parables” mostly means, “Jesus was a stupid peasant who told misleading stories that we have to carefully strip down to a single point that we found in Paul’s Epistles”–or rather, “that we found in Westminster Confession” (or, “… the Councils of Trent” or whatever). I’m going to go out on a limb and guess that God isn’t blessing churches who don’t like the Bible.

7. Preach Jesus as King but Avoid Petty Politics

Jesus is Lord and he wants a visible unified entrance to the Kingdom (Church) as a witness to that fact. We have to obey what Jesus says, but we also have to recognize how divisions and arguments actually can undermine the theocratic Faith. So find some highly obvious points in the public square to harp on (i.e. abortion), but try not to get bogged down in minutia (don’t preach Christian libertarianism, socialism, or whatever from the pulpit).

8. Let the Great Commission be your commission

If you think you know what this means, go read it, and ask yourself what this says about being “born again,” “faith,” or “evangelism” compared to what it says about obedience, theocracy, baptism, and ongoing teaching/training of everyone.

9. Worship like the Bible matters

Does it not strike anyone as odd that, if you want to attend a worship service that took you systematically through Scripture, you would be better off in an Episcopal, formal Lutheran, Roman Catholic, or Eastern Orthodox service rather than a Baptists, conservaitve Presbyterian, or “Bible Church” assembly? Is God supposed to speak to us in the Church or not? If not, how are we supposed to see anything change, let alone the world?

10. Live Corporately like Matthew 18 is in the Bible

I mention the whole chapter on purpose, by the way, because it is obviously focused on humility and forgiveness, and in that context gives directions for accountability and purifying the Church. I think that is important because, while not one church in a hundred includes Matthew 18.15-19 in their real canon, some that do can be so zealous (I’m using a euphemism) about it as to reinforce the temptation to neglect it. But it is in the Bible and it is an operating instruction from the Lord Jesus. So obey Him.