1. If you belong to a small sect once, recently, or potentially separated from the broader stream(s) of the church, and you believe your group alone to be God's people and the one true church or believe that the end is imminent and that that end is intimately related to your own group's existence -- you are not the first, nor the last, and chances are you're wrong.
2. If you believe you have arrived at the definitive doctrine of x, or the decisive interpretation of y, and that that doctrine or interpretation, by its novelty or brilliance or significance, has once and for all solved problems a, b, or c, or delivered the church universal from prior missteps to the left or to the right -- chances are you haven't, and it doesn't; and that is okay.
3. If you find yourself bewildered or belligerent in response to a newfound scientific discovery, philosophical idea, or theological proposal, suspecting that, if accepted, it will either destroy the church or irrevocably bedevil civilization -- be patient: the church will adapt, cultures will absorb, and the still-fallen world will keep turning. Do not lose your vigor -- evil and falsehood still demand confrontation! -- but keep from falling into apocalyptic fanaticism.
4. If you come to a time when all seems well or life is hell, and the former leads you (or the world) to believe that you have finally "arrived" after centuries of remarkable progress (whether providential or anthropological) or the latter leads you (or the world) to believe that the world is worse than it has ever been before and all is lost -- slow down. There have been better ages, and there have been worse ages, and usually both are present simultaneously in different parts of the world, because whatever it is you are going through it is not the universal experience of the whole planet.
5. If you feel the need to take an unequivocal stand on some aspect of Christian faith or practice, and you would like to be validated, vindicated, or celebrated by subsequent generations, make sure you are really, really, really, really, really certain that the issue is worth it. History is a harsh judge, and does not know the fleeting passions of your age.
6. If something seems self-evident, it almost certainly is not. Especially regarding heresy. Also regarding authority, God, gender, violence, law, sacraments, science, sex, salvation, sin, ethics, sickness, Scripture, ministry, mission, tradition, and truth. To name a few.
7. If you are confronted with a person, group, or situation that seems to demand that others be killed and/or that you should participate or bless or baptize that killing and/or that the justification of that killing is grounded in Christian logic -- just stop immediately. They shouldn't, you shouldn't, and it isn't. Do not take up the long tradition of adding more and more innocent blood to the guilty hands of the church. There is already enough, and much of it is Christian.
8. If you discover that your welfare, livelihood, future, popularity, power, pocketbook, or message is tied up inextricably with the welfare, livelihood, future, popularity, power, pocketbook, or message of a particular ethnic group, region, or nation-state -- extraction must be the immediate project. God has not acted anew to anoint a chosen nation, nor may any group be so Christianized as to be synonymous with Christ's church, nor does God show favoritism to any people group. Expel the syncretism from among you!
9. If you encounter a perspective or practice that seems absolutely unthinkable, rest assured that your forebears encountered things you take for granted with similar incredulity, as will future generations concerning whatever is bothering you at the moment. This is simply a fact. Be conscious to take it into account; it can get embarrassing when later persons recall your life and work.
10. If you look around and are inclined to pronounce a golden age upon the state of the church evident to you at a particular time, even if this is so do not fall for the temptation -- the church ebbs and flows in times good and bad, and the peaks and valleys are unavoidably and unpredictably notorious in the violence of their upheaval and change. Whatever unfaithfulness has been extinguished for a time will return in time, and whatever faithfulness has arisen will similarly fall away. Heed the theological dictum: the church is made up of sinners. If nothing else, do not believe otherwise!