It shouldn't need to be said that there is nothing in the Biblical text that supports an old earth. On top of this, throughout history, the overwhelming majority of both Jews and Christians recognised either the same or a similar time frame presented by modern Biblical Creationists. James Ussher, Anglican Archbishop of Armagh, even came up with what he believed to be the very date of creation long before Charles Darwin or Charles Lyell were even born.
So old earthers have quite the uphill battle. They fight against the text, they fight against history, they even fight against science (as Evolution and the Old Earth are very much not scientific). Worst of all, in fighting against these things, they ultimately fight against God. All of this, and they still lose, but for what cause? Ultimately, the acceptance of Theistic Evolution and other old earth philosophies centres around unbelievers and their opinion of Christianity.
A lot of old earthers even admit this. Their arguments are often "but if we support a young earth, unbelievers will think we're crazy!" But in reality, this attitude backfires. Firstly, it backfires because, let's be honest, creation isn't the only miracle the Bible presents. Christianity, by its very definition, is a miracle. There are no natural explanations for how a man can be born to a virgin woman, or how that same man can perform numerous supernatural signs throughout His ministry, or for how that man can be beaten half to death, nailed to a cross to die, then after being stabbed in the hip to verify His death and laid in a tomb for three days, He got up. My friends, if you don't want to believe in miracles, Christianity is not the faith for you.
But secondly, it fails because unbelievers possess this amazing ability called "reading". An atheist, or an agnostic, can access every piece of information available to you. They can access a Bible, and it doesn't even take 8 pages to see that the Bible is very much a Creationist book. It explicitly presents a 6 day creation week, it posits a global flood, it describes the dispersion of the nations from a single city, and if the atheist is diligent enough, they can see that the rest of the Bible circles back to that. Peter even went so far as to link creation and the flood to the return of Christ, and how denial of one leads to the denial of the other (2 Peter 3:1-9).
The difference between an atheist and a Theistic Evolutionist is that, while the latter is willing to compromise in order to save both beliefs, the former has no such motive. To an atheist, the Bible is not an authoritative source. They have no motive to reinterpret it so it fits with their other beliefs. Rather, when the Bible disagrees with what they already believe, they can afford to just let it say what it says, then deny it is right to say it. So, what does compromise really say to an atheist? "Don't bother believing our Bible. We don't believe it either."
Think about it this way: What's the one thing all atheists hate about Christianity? Hypocrisy! When we preach about charity, yet spend more money building elaborate churches than homeless shelters, they see hypocrisy, and they hate us. When we preach peace and love, yet we are hateful to sinners even within our own congregations, they see hypocrisy, and they hate us. When we preach about an afterlife, yet concern ourselves far too much with what happens in this life, they see hypocrisy, and they hate us. Even when I got my first tattoo (this was before I had even fully read the Bible), I remember an atheist commenting on one of my videos: "Someone doesn't read his own Bible", and he posted, of course, Leviticus 19:28. Out of context, granted, but it does show that atheists are capable of reading the Bible, and they will bite us if we don't at least give the appearance of faith.
I will never forget two atheist boys who spoke with me. Their friend was offended by something I'd said about religion, so she added them to the conversation, and they were very aggressively mocking Christianity. I couldn't get a word in edgewise, but they of course started mocking the ark. Because they hadn't really let me talk, they didn't know a thing about what I believed. The result: They started mocking me as if I was an old earther. "Oh, but of course, that's just an allegory isn't it? Because even you know the Bible is bull!"
My friends, old earth compromise is deadly. It took a whole civilisation that was relatively friendly to Christianity and allowed atheism to fester, and grow, and now, after just a few generations, my own home country is anything but Christian, with something like 14% of people attending church on a weekly basis. And I can assure you, they are not all faithful. People are leaving the faith because of old earth philosophies, people are refusing to join the faith because of old earth philosophies, people are dying, both physically and spiritually, because of old earth philosophies. This is not a game, this is not a matter of personal preference, this is a matter of eternal life and the second death.
Will God be pleased with this compromise? Even if you are truly washed by the blood of Christ, that does not change the fact that you were soaked in the blood of unbelievers. While you are in Heaven praising the name of God, people in Hell will be cursing the name of you, because you gave them permission to reject the faith by rejecting some of it yourself. So old earthers, it is time to pick a side. If you are not Christians, stop pretending to be. Apostatise and make our jobs easier. If you are Christians, repent, believe the Bible, and help us save souls. The Church does not need more heretics, for it has had too many of those since the beginning. Rather, it needs faithful believers who will obey Christ, making disciples of all nations, baptising them, and teaching them to obey all that Christ has commanded. Pick a side: The truth, or the lie. For Christ's sake, and your own, pick the truth.