While we can get by with scripture alone, it is through the study of theology we can gain a better understanding of what we've read in the Bible how we can articulate those truths.
The definition of Theology is the study of God, that is, God (theo) & study of (ology). The prejudicial notion of this being only a discipline of those more gifted intellectually than we are is the farthest from the truth as when we study it, we know God with much greater clarity.
Now of course there are terms, doctrines, & theologies used are foreign to us, but terminologies & concepts are often the result of in-depth studies.
Terms such as Parousia, Regeneration, & Ecclesiology are not in scripture & yet when you them up your eyes will be opened for each one reveals deeper truths of Jesus, salvation, & the church we do not see at first reading.
Now, doctrine simply another word for - teaching. When you read the bible, you are not just reading history & morals but doctrines as well (you're just not seeing the official names of). For example, the Doctrine of the Trinity is a teaching of what God is; the Doctrine of Justification, that is, the teaching on what & how we're saved; finally,
Finally, theologies are bodies of knowledges that is on a concept. for example is Theophany (the appearance of God in scripture), Angelology (the study of Angels), Christology (the study of Christ), & Eschatology (the study of the end times).
"NO - BIBLE ONLY!"
For those of you who believe that we should study the Bible alone for the sake of simplicity & humility (as knowledge puffeth up - 1 Corinthians 8:1), if you truly have studied scripture then it should drive you to learn theology. When you read Matthew 24 wouldn't that create in you a thirst to know more about it? Wouldn't that drive you to learn about Eschatology?