Since Biblical Theology has sometimes been associated with "modernism" or "liberalism," it is important to note that conservative Evangelicals also have their own way of doing Biblical Theology. But is is even more important to explain exactly what "modernist theology" is.
Beginning in the late 18th century, some European theologians began to doubt the supernatural aspects of the Christian faith and the authority of the Bible. This was largely due to the influence of secularized philosophy with its emphasis on human reason and the scientific method. As they applied these principles to the Bible, they began to doubt its historical accuracy and its inerrant nature. For many, the Bible was still special, because it was a "witness" to God's revelation, but it was no longer considered the divinely inspired Word of God.
Consequently, they reacted against the "dogmatic" position of traditional Christianity, and could no longer defend key doctrines such as the virgin birth of Christ, His literal resurrection, and miracles in general. For some, this may have been an attempt to save the Christian faith from being totally eliminated by secularism, but the result was actually devastating. This movement came to be known as "liberal theology" or "modernist theology."