This is classic. What do I mean by "classic"? Not the first definition -- "judged over a period of time to be of the highest quality and outstanding of its kind." No. I'm using its second definition -- "very typical of its kind." It is a common type ("typical") of argument for this discussion. I've seen it in multiple places. Should women be allowed to be pastors in churches? Well, since a lot of churches allow it now and none ever did before, clearly they've been arguing about it for a long time, so we can't know which is right. The Mormons, the Jehovah's Witnesses, and the Oneness Pentecostals (to name a few) might argue, "The doctrine of the Trinity has been debated almost since the beginning of Christianity. If they couldn't figure out which is which, I'm sure we can't." See? Classic.
The response, however, while being classic -- a typical response -- is not a good response. You see, if "It has been debated so we can't know" is the argument, then we can't know ... just about anything at all. Most of science, all of philosophy, and a vast array of moral issues have all been debated, so we can't know what's right. Since the greatest concern to Christians is God and His truth, this argument would put an end to all of that. They've debated the existence of Adam, Noah, Moses, and Jesus for a long time. We can't know. Loud voices tell us the Bible is not truth, but "myth" ... at best. We can't know. Did Jesus die for our sins? Lots of people disagree, so we can't know. Is there even a God at all? A growing cacophony of voices says He does not, so we can't know. You see, if you take this as a standard, the best we get is not faith, but a nebulous opinion.
It isn't, of course, being used this way. This is the logical conclusion, but they don't conclude that way. What is really intended is "I don't want to think about it because I don't have any arguments to match yours or, more likely, I've never even considered it, but it is not my intention to pursue such a consideration, so drop it." It's a high-sounding smoke screen. "Don't bother me with facts; I know I'm right." Now, of course, maybe you'd disagree. If you were willing to admit "We can't know anything as true ... especially as 'God's truth'," then maybe I'd think that you were serious. And some do. I know. Some consider it a "higher position", a better place. "Don't think you can know anything as certainly true." "It's more humble," they say, forgetting that it's also self-contradictory because you do claim to know for sure that you can't know anything for sure. But it cannot be considered as conducive to faith or to Christianity. Faith, you see, is defined as "being convinced" and "being convinced that you must not be convinced of anything" is not faith. Christianity, further, is premised on faith.
I get it. I really do. Too much bluster and babble and battle is poured out over some topics. We seem to forget that, while we are indeed supposed to always be prepared to "make a defense to anyone who asks you for a reason for the hope that is in you" (including other Christians), we are supposed to "do it with gentleness and respect" (1 Peter 3:15). We are to contend for the faith (Jude 1:3) and speak the truth, but we are to do it in love (Eph 4:15). I get that too often too many get too agitated to have a discussion, an exchange, a dialog on what is and isn't true. But let's not let that be us. Let's not give in to foolish arguments that undercut everything in order to avoid pursuing the truth into which we are led by the Spirit (John 16:13). In the words of a bizarre TV show, "The truth is out there." Of course, Jesus said it best.
"If you abide in My word, you are truly My disciples, and you will know the truth, and the truth will set you free." (John 8:31-32)Don't miss the key point. "If you abide in My word." Don't miss the promised conclusion. "You will know the truth." Don't buy the "we can't know" argument. Jesus said otherwise.