Of course, it will depend on who you ask. Most religious people would not agree with that statement.
There is, the little matter that "religion explains things that cannot be explained" is an oxymoron (if they can't be explained, then nothing can explain them). Let's leave that aside.
If you look at, for example, Thomas Aquinas, the Summa Theologica has a lot of explaining that takes place in it. He explains things in pain-staking detail. The same goes for much of Augustine's work (see, City of God, On the Trinity as two examples that are more like this). There is also a great tradition among Jewish philosophers (Moses Maimonides, Philo) and Muslim philosophers (ibn Sinna, Averroes as just two examples) of explaining rationally different aspects of God. So, based on that, it doesn't seem quite right to say that religion is only about the unexplainable (or, as is sometimes stated, the "irrational").
To take this a bit further, if you look at anyone of Augustine (Confessions), CS Lewis (Surprised by Joy), or Thomas Merton (Seven Story Mountain) as examples, there are many people who felt logically the need for God's existence before believing in any particular religious tradition. If you believe what they have to say, that points that to some degree God is knowable just based on natural law before knowing anything about, or believing in, revelation. They would disagree with the idea that religion/theology is just some separate (and therefore unnecessary!) sphere.
To get to your question about how to write a quote that distinguishes between science and religion, I feel there are a few approaches:
- Science is evaluated by the scientific method with empirical data. Religion is evaluated by a mixture of historical methods and internal experiential data.
- The focus of theology is to know God better, the focus of science is to understand matter better; sometimes (of debatable frequency: some would argue for more often, some less often) they happen to inform each other.
- Religion explains the purpose behind things, science explains simply how they happen. (Most atheists I know reject this saying that many things just don't have a purpose.)