When making a case, it's important to not only consider who you are, but also who your audience is. It is important to consider who you are because, obviously, you're presenting your case for your worldview. You won't see a Christian or an atheist arguing from the Qur'an, for example, because neither believe the Qur'an.
There is, however, an exception. If your intended audience are Muslims, it makes sense to argue from the Qur'an, not because you believe it, but because they believe it. Thus, you can find things in the Qur'an that are supportive of, sympathetic to, or at least consistent with your view.
Now, in a discussion between two Christians regarding the Trinity, would you ever expect either to so much as reference the Qur'an? What would you think of a supposed Christian who recognises that the Bible does present the Trinity, but then points out that in Qur'an 4:171, Allah tells us that the Trinity is excessive, Jesus is only a created being, Allah has no Son, and therefore Christians should "say not three"? You'd think that guy was not a Christian, but a Muslim! He believes what Muslims believe, he argues the way a Muslim would argue, and he even expects that you will esteem the Qur'an so highly that whatever the Bible says, you will agree with the Qur'an instead.
Now, the Trinity is an essential issue. You cannot be a Christian and reject the Trinity. To be saved, one must confess Jesus as Lord (Romans 10:9), which denying His divinity is the antithesis of. And those who blaspheme the Holy Spirit (blasphemy being the sin of denying God's divinity in some way) will not be forgiven in this life or the next (Matthew 12:32; Mark 3:29). Therefore, you literally cannot be a Christian and deny the Trinity. You can, however, be a Christian and believe in Evolution. It's extremely inconsistent, but does not explicitly deny anything essential for salvation.
That being said, just as you would never expect a Christian to argue from the Qur'an, and assume anyone who does argue from the Qur'an is a Muslim, you would never expect a Christian to defend Evolution, to a fellow Christian, from anything other than the Bible. Yet they do! Theistic Evolutionists do occasionally argue from a few heavily twisted Bible verses, but they primarily argue from a Naturalistic view of science, just like atheists.
If Evolution was compatible with scripture, it would be easy for Theistic Evolutionists to argue from scripture. Creationists do this all the time. When I argue against Evolution to an atheist, then I will argue from science, right down to showing the absurdity of Naturalistic assumptions. With them, I don't argue from the Bible primarily (while also not abandoning it) simply because I know they don't accept the Bible. But I can show from science and history that the Bible's view of origins is the better option, and Evolution is unworkable.
With Christians, however, I default to scripture. Why? Simply because being Christians, the Bible should not only be our common ground, but our ultimate authority. It is the infallible book of the omniscient and sovereign God we both claim to worship. I accept the Bible as true and authoritative, and I assume the Theistic Evolutionist does, too. And if the Theistic Evolutionist both accepts the Bible as true and authoritative, and believes I do too, it would be easy, if his view was valid, to also argue from scripture.
Instead, they argue from a Naturalistic interpretation of science because that is their primary authority, and they expect it is yours, too. Like our hypothetical "Christian" who is actually a Muslim, they stray from the Bible, arguing from a completely different source, because they not only assume that source is more important than what the Bible says, but also hope you will likewise abandon the Bible if they can convince you science tells you to.
Naturalism, which is the only philosophy that would even allow for Evolution in science, is by definition atheistic. It is the assumption that the natural world is all that exists. That there is no supernatural, and things have always worked the natural way. The way things are now is the way they have always been, and these natural processes not only explain how things are, but how they came to be. It is specifically designed to rule out God, ironically separating Him from the very field of study His people invented to understand Him better.
But only an atheist could be so hateful towards God that they cling to a whole philosophy invented specifically to deny Him. When we remove Naturalism from science, we have no need to give any wiggle room to magical explosions that make organised galaxies, nor magical microbes that spontaneously come into being in a sludge pool, only to give rise to millions of creatures over millions of years. We need to give no credibility to monkey men, nor do we expect anything to reproduce except according to its kind. We don't need any of that, and can quite happily allow for the Creation account in Genesis to be true.
With an atheist, it makes sense to use science and history to show that it is, along with logic to show that Naturalism is an unnecessary assumption. But by default, if you are a Christian, you should already accept that it is true. Since Theistic Evolutionists instead default to arguing in atheistic ways for an atheistic worldview, there are only so many ways we can interpret that.
By default, since origins is not an essential issue, we should be charitable to Theistic Evolutionists. By default, we should assume they are saved until they demonstrate beyond reasonable doubt that they are not. Christians, after all, will never be infallible. We will always make errors, and no, we are not immune from sin. Sin blinds us even to God's truth. Thus, we can assume that Theistic Evolutionists are Christians who are either too lazy to study the scriptures, or too filled with pride to surrender their origins views to God.
But as Jesus says, you shall know the tree by its fruits. What kind of fruit is Evolution? An atheistic one. Both by nature, and in effect, Evolution is an atheistic fruit. It is an atheistic origins myth, standing in contrast to God's creation account, and it leads to atheism in faith, and even in practice. Therefore, although a Theistic Evolutionist may be just a Christian in error, it may also be a symptom of atheism.
I will never be able to say Theistic Evolutionists are not saved. After all, there was a time in my own faith when I knew the Lord, but not His word, and thus I myself needed to shed some compromises. Nevertheless, my heart fears for those who would hold to such blasphemous heresies. To charge God's word with such error, to trivialise it with such flimsy methods of interpretation, to concede so much ground to the devil, is almost as scary to me as Peter's hypocrisy when, fearing the Jews, he isolated himself from Gentiles (Galatians 2:11-13). I earnestly urge Theistic Evolutionists to pick a side. Repent, reject the atheistic Creation myth, and stop arguing in its defence as the atheists do. But if this seems wrong to you, then let us speak about science, but with you as the atheist you are. If you will not hear God's words, stop claiming Him. Then we will talk science, and you will see why leaving Him at all, much less for Evolution, was the silliest decision you ever made.