You've seen plants referred to by their scientific names, such as Rosa rubiginosa. That form of naming plants and other living things was introduced by a Christian who was a scientist named Carolus Linnaeus. He was born in Sweden in 1707 to a Lutheran pastor. He showed interest in nature from his childhood, and eventually pursued science at the University of Uppsala. His interest was motivated by a theme that keeps popping up among Christian scientists featured on this blog: They believed the world was created by God, and therefore orderly, and able and worthy to be studied. This is the principle that generated tremendous scientific investigation.
Linnaeus developed the modern taxonomy system. Though it's been changed over time, it is the basis for categorizing and naming living things.
For Linnaeus, species of organisms were real entities, which could be grouped into higher categories called genera (singular, genus). By itself, this was nothing new; since Aristotle, biologists had used the word genus for a group of similar organisms, and then sought to define the differentio specifica – the specific difference of each type of organism. But opinion varied on how genera should be grouped. Naturalists of the day often used arbitrary criteria to group organisms, placing all domestic animals or all water animals together. Part of Linnaeus' innovation was the grouping of genera into higher taxa that were also based on shared similarities. In Linnaeus's original system, genera were grouped into orders, orders into classes, and classes into kingdoms. Thus the kingdom Animalia contained the class Vertebrata, which contained the order Primates, which contained the genus Homo with the species sapiens – humanity. Later biologists added additional ranks between these to express additional levels of similarity.
Linnaeus based plant classification on their reproduction, which was considered rather scandalous at the time. "[O]ne opponent, botanist Johann Siegesbeck, called it 'loathsome harlotry'. (Linnaeus had his revenge, however; he named a small, useless European weed Siegesbeckia.)"
Linnaeus experimented with hybridization of plants and animals. But he rejected the notion of evolution, which was already introduced at his time long before Darwin popularized it. He believed that there was a limitation in the changes a species could undergo, being set in its creation. The potential for change was present at God's creation.
The concept of open-ended evolution, not necessarily governed by a Divine Plan and with no predetermined goal, never occurred to Linnaeus; the idea would have shocked him. Nevertheless, Linnaeus's hierarchical classification and binomial nomenclature, much modified, have remained standard for over 200 years. His writings have been studied by every generation of naturalists.