2 Peter 3:8-9

8 But do not let this one fact escape your notice, beloved, that with the Lord one day is like a thousand years, and a thousand years like one day. 9 The Lord is not slow about His promise, as some count slowness, but is patient toward you, not wishing for any to perish but for all to come to repentance.

The key words in these verses are “His promise,” meaning the promise of His coming to bring judgment with fire (v. 7). In verse eight Peter implied that God sees time differently than we do. He sees all the days of one thousand years just as clearly as He sees one day. He is a transcendent eternal being. He is not restricted by the passage of time as we are. He exists in an eternal present state. God has given us the laws of time so that we may be accountable for all that we do in our life. But He exists outside of those restrictions.

Hence, if we think that the Lord is slow in His coming, He is not—even as we count slowness. He is waiting for us to come to Him in repentance so that we will not perish by His judgment.