Thank you for the question on defending or explaining the Scriptures, “What is universally the toughest Bible scripture for a pastor/preacher to defend?”
As a retired pastor, there are Scripture verses that are difficult to explain or defend when questioned. Believers what their pastor to explain while agnostics or atheists want the pastor to defend a Biblical view. One must be careful that although it may be difficult to defend or explain the Scriptures from scientists as astronomers, geologists, archaeologist, it does not mean that the Scriptures are indefensible.
Here are four Biblical and theological questions that have been posed to Christians including pastors:
1. The defense of the creation account in light of scientific theories or evidences for the age of the universe and earth (Genesis 1).
2. The defense of the enslaved Jews from Egypt to the Promised Land from an archaeological evidence viewpoint (Exodus 1–14).
3. The defense or explanation of God’s sovereignty and man’s free will (Romans 9).
4. The defense of the existence of God (Genesis 1:1–3).
In my opinion, none of the above should surprise any agnostic, atheistic. or Christian. If anyone has been on Quora for any length of time, one would know the pros and cons of those arguments as one can also listen to debates between Christian apologists and atheist apologists that even includes textual criticism.
Christians are called to study the Scriptures to be able to give the reason for the hope that one has in Jesus Christ. It is true that Christians do not have all the answers on every subject as the Bible is not a scientific book nor is it a fairy tale book in my opinion. Christians are called to be knowledgeable of the pros and cons so that one can speak or write reasonably on the topic that is being posed. Christians ought to be more thoughtful in their answers without overreacting to a question. I had to learned that and am learning that.
SUMMARY: The Bible poses a world view that is diametrically opposed by our modern world. Is it really a lack of evidence from the Bible or is it really the rejection of the existence of the Creator God?
For more perspectives: