And why is that, when Peter was speaking about "these things" also in Paul's Epistles?
2 Peter 3:14-1614 Wherefore, beloved, seeing that ye look for such things, be diligent that ye may be found of Him in peace, without spot, and blameless.
15 And account that the longsuffering of our Lord is salvation; even as our beloved brother Paul also according to the wisdom given unto him hath written unto you;
16 As also in all his epistles, speaking in them of these things; in which are some things hard to be understood, which they that are unlearned and unstable wrest, as they do also the other scriptures, unto their own destruction.
KJV
I don't find Paul's teachings about the law and grace being all that difficult. The "some things hard to be understood" is about the subject Peter was covering there in that 2 Pet.3 chapter of world ages. Can someone tackle the Romans 8 Scripture by Paul concerning the creature?
Yes, I take the "hard to understand things" Peter is referring to in context is Paul's treatment of future events e.g. in First and Second Thessalonians. Which some were over turning the faith of others by saying the Day of the Lord had come.
Here is the context...
2 Peter 3:3-14 (HCSB)
3 First, be aware of this: scoffers will come in the last days to scoff, following their own lusts,
4 saying, "Where is the promise of His coming? For ever since the fathers fell asleep, all things continue as they have been since the beginning of creation."
5 They willfully ignore this: long ago the heavens and the earth existed out of water and through water by the word of God.
6 Through these the world of that time perished when it was flooded by water.
7 But by the same word the present heavens and earth are held in store for fire, being kept until the day of judgment and destruction of ungodly men.
8 Dear friends, don't let this one thing escape you: with the Lord one day is like 1,000 years, and 1,000 years like one day.
9 The Lord does not delay His promise, as some understand delay, but is patient with you, not wanting any to perish, but all to come to repentance.
10 But the Day of the Lord will come like a thief; on that [day] the heavens will pass away with a loud noise, the elements will burn and be dissolved, and the earth and the works on it will be disclosed.
11 Since all these things are to be destroyed in this way, [it is clear] what sort of people you should be in holy conduct and godliness
12 as you wait for and earnestly desire the coming of the day of God, because of which the heavens will be on fire and be dissolved, and the elements will melt with the heat.
13 But based on His promise, we wait for new heavens and a new earth, where righteousness will dwell.
14 Therefore, dear friends, while you wait for these things, make every effort to be found in peace without spot or blemish before Him.