In the last post, I claimed that there is value in Christians seeking to know the truth about the age of creation. In particular, I suggested that those who would be teachers (or pastors, evangelists, or apologists) ought to teach only that which they know to be true. So the question comes up, how do we know how old the universe and Earth are?
Let me first frame my answer in very general terms, not having in mind the age of creation but any question about which there are two dissenting views. In such a case, and before one is qualified to teach on the subject, one ought to...
1) Study as much of the relevant evidence as is necessary to have a full grasp of every facet of the issue.
2) Read widely on both sides of the issue, not just proponents of the view to which you are already inclined.
3) Where you remain dependent on the arguments of others, ascertain the qualifications of those sources to weigh in on the issues.
4) Examine the arguments made by proponents of both views (for validity, truth of premises, cogency).
5) Interact with the strongest (not the weakest) arguments of each side, particularly of the view with which you disagree.
6) Never mischaracterize the view of either side, particularly the one with which you disagree.
7) Treat those with whom you end up disagreeing with the utmost respect.
These steps are easily understood, and amount to nothing more than common sense. Basic courtesy, let alone Christian charity, would seem to dictate that we follow them.
And so, if either you or the friend with whom you disagree cannot honestly say that you have followed each of these steps, then a level of uncertainty and humility should characterize whatever discussions you have, and those discussions should definitely remain intramural. That is, neither of you should teach on such an issue until you can say that you have done the necessary research.
All that said, there's an even more basic issue that may need to be settled regarding the specific issue of the age of the creation. The steps discussed above apply to any case where there are different views or interpretations. Among Christians, such disagreements often (as in the age issue) involve differing interpretations of Scripture. But on this particular issue, it is common for proponents of the young-earth interpretation to pretend as though they are defending Scripture itself, rather than an interpretation of Scripture.
If (and now I'm speaking directly to the reader who posed this question) your friend cannot first acknowledge that his view is an interpretation (if , instead, he believes it is "what God's Word says"), then I submit that you will never help him to reach truth on this issue.