Explain "I could wish you were cold or hot" in Revelation 3:15

Re 3:15 "I know your works, that you are neither cold nor hot. I could wish you were cold or hot.
16 "So then, because you are lukewarm, and neither cold nor hot, I will vomit you out of My mouth.

First of all, some background. Laodecia was known for lukewarm water that was unacceptable to many who drank it. People there were known to spit their water out. On the northeast, they sourced hot water, while on the southeast, warm water.

The city of Laodecia built aqueducts to obtain these waters. But as they got to Laodecia, these waters became lukewarm from the combination of both the hot and cold.

Now, when the Lord Jesus said here: "I could wish you were cold or hot" He was saying that an extreme, clear and unmistakable spiritual condition would be better than what there state was, which was lukewarm.

You see, their lukewarm spiritual condition was deceptive. A lot of them thought that they were blazing, sizzling and passionate enough for God, that they were okay with God. But they were actually unacceptable --- lukewarm.

 Re 3:17 "Because you say, 'I am rich, have become wealthy, and have need of nothing' --and do not know that you are wretched, miserable, poor, blind, and naked--
18 "I counsel you to buy from Me gold refined in the fire, that you may be rich; and white garments, that you may be clothed, that the shame of your nakedness may not be revealed; and anoint your eyes with eye salve, that you may see.

Why did the Lord Jesus prefer that they were either hot or cold?

Because, if hot, they can be truly encouraged to go on. If cold, they could easily detect what's wrong with themselves and be more open to a much needed rebuke.

Explain "The Sting Of Death Is Sin"

1 Co 15:56 The sting of death is sin...

By "death" here is meant the death of the unsaved, those whose sins are unforgiven.
By "sting" here is the power to harm.

The death of the unsaved has a sting. It is harmful. Because unforgiven sins will always be met with divine judgment after death. On the other hand, the death of the saved sinner is gain.

Php 1:21 For to me, to live is Christ, and to die is gain.

The death of the saved has no sting in it. Death for the saved sinner is described as being asleep in Jesus. It carries a blessed prospect of being awakened in a glorious resurrection at the Rapture.

1Th 4:14 For if we believe that Jesus died and rose again, even so God will bring with Him those who sleep in Jesus.

How Do I Discover The Will Of God?

The will of God is discovered primarily through God's Word --- its precepts and principles.

In addition, many Christians who want to discover the will of God focus on the areas of what they should be doing. Actually, what they should be focusing primarily is not on their doing but their being --- character.

Christlike character first then the discovery of God's will second. Once you have the character it is easy to choose the course as to which you will take. In most cases, our struggle is not really about what to do --- many a time it's plain and clear. The real struggle is really with ourselves. We (because of our characters) want to do something else.

Ro 12:2 And do not be conformed to this world, but be transformed by the renewing of your mind, that you may prove (or know by experience) what is that good and acceptable and perfect will of God.