“Wherefore the rather, brethren, give diligence to make your calling and election sure: for if ye do these things, ye shall never fall:”
2 Peter 1:10

“…and to virtue, knowledge” 2 Peter 1:5
The word knowledge there can be expatiated as knowledge gained by studying, and the word of God admonishes us to study:
“Study to shew thyself approved unto God, a workman that needeth not to be ashamed, rightly dividing the word of truth.” 2 Timothy 2:15
You can’t afford to be an ignorant Christian, ignorance has a certain result- destruction:
“My people are destroyed for lack of knowledge…” Hosea 4:6
The word of God is telling you to be diligent in your study, take your Bible study time seriously, seek to increase in your knowledge of God, don’t just settle to hear the bible being explained or quoted from the lips of someone else- give diligence to know the word yourself.
You can’t express moral excellence when you don’t even know the standard for such excellence.
Being born again is a marvel, now desire the word, desire to grow- diligently study and increase in knowledge.
“As newborn babes, desire the sincere milk of the word, that ye may grow thereby:” 1 Peter 2:2
“But grow in grace, and in the knowledge of our Lord and Saviour Jesus Christ. To him be glory both now and for ever. Amen.” 2 Peter 3:18
He says if you give diligence to studying and increasing in knowledge, you shall never fall.