What is the best way to study the Bible in depth? Do I have to learn Hebrew or even Greek?
There is no single “best” way to study the Bible. Many different approaches can be helpful. You definitely do NOT have to know either Greek or Hebrew to have a very in-depth knowledge of the scriptures. We have access to an almost infinite amount of material by scholars on the various meanings of individual words and phrases, as well as access to the various ways in which a particular passage is understood by the experts. For this reason, not having knowledge of the original languages is not a serious impediment to knowing and understanding the Bible. If you want to be a serious student of the scriptures, my first suggestion is that you take a class on biblical hermeneutics. You should also plan on eventually getting good commentaries to Bible books which you want to study in depth. You might want to eventually take some graduate level classes in theology, biblical interpretation, and other specialized topics if you want to really take it higher. What you need is to develop a plan based on how in depth you want to take your study of the Bible. The plan should have a short-term, a medium-term and a long-term goal. For example, I have a long-term goal to know every single book in the Bible in-depth. This is a roughly 20 year long-term goal. Every six months or year I set a goal to learn two or three books in-depth during that time. That is my medium term goal. Then I have short term goals in any given week or month to make progress toward that goal.
Also, although you do not need to know the languages, if you can study some of the history and the culture of the Jews, the early Christians and the surrounding groups, that can be very helpful. I suggest that once you become well-grounded in the Bible, you should spend some time studying Christian theology. A study of Church History can also be helpful.
All of this will take time, effort and perhaps even a significant amount of money. But it will be fun, rewarding and inspiring and it will make your life more productive for God. I say go for it.
Here is a link for a class on hermeneutics at the web site: https://evidenceforchristianity.org/class-on-hermeneutics/ Also, I am attaching a set of notes on getting the most from your Bible study which might be helpful. Great Bible Study