³ to those who persistently and patiently wait for him he will appear a second time, not to bear sin, but to bring salvation.

to those who persistently and patiently wait for him

This verse has been typically translated as who have been waiting for and expecting him; of course the translators were all from Babylon with no teaching from the Holy Sprit, so they didn't even understand what "waiting on God" meant, despite many Old Testament and New Testament references. The original Greek for this verse shows that the Greek word translated as waiting is apekdecomenoiv which means "assiduously and patiently waiting for," and "assiduously" means "persistently;" so the correct translation "who persistently and patiently wait for him." By your steadfast endurance do you possess your soul. Luke 21:19. To wait on God is to persistently and patiently sit in humble silence, listen for his voice and words, watch for his revelations, hear his commands, and then obey Him. This is the key to spiritual growth: to wait on God, listen, and watch; this is part of the cross. This is how to sit at the feet of Jesus and listen to his words, which Jesus told us was the "good part" and "only one thing needed:"

 And she had a sister called Mary, who also sat at Jesus' feet and heard his word.
"There is only one thing needed, and Mary has chosen the good part, which shall not be taken away from her." Luke 10:39,42

We hear his word from within our hearts. Rom 10:8,17. The words he speaks to us are spirit and life-giving. John 6:63

The one thing needed is to sit at the feet of Jesus and listen to his words, the words he speaks to us from within our hearts that are spirit and life. We too must sit silently and wait on the Lord, to listen, to hear, and obey.

Notice also: what she hears will not be taken away from her. Those teachings will survive passing through the fire that everyone must endure.

All your holy ones are in your power. And they sit at your feet, each receiving your words. Deu 33:3

To wait on God, listen, watch, and obey is the cross, which is the way to purity and salvation, the deliverance from all sin.

Despite the fact that the Bible is full of testimony regarding waiting on God both in the Old Testament and the New Testament; and that waiting as the key to salvation in Old and New Testaments was also referenced many times; Christendom reads this verse and thinks waiting for Him is waiting for Him to answer their prayers or waiting for Him to physically come to the earth to judge all. So Christendom's waiting is singing about Jesus coming, hoping for war in the Middle East that might signal his soon return, speculating on how the mark of the beast will be forced on everyone, speculating on who is the antichrist, etc. For many centuries Christendom has missed Jesus, waiting to reveal himself in every man who heeds and obeys Him, just like the Jews missed Jesus because they were looking for a physical king to come and rule. The New Testament is full of references to the second appearance of Jesus being then, not thousands of years later. In Matthew, Mark, and Luke, Jesus is recorded saying that some then standing with him, 2000 years ago, would see his glorious coming in the clouds with the Kingdom before they died. In addition Paul, Jesus preaching, Jesus in Revelation, Peter, James, and John, — all said, soon, the time is near, a little while, he stands at the door. Christendom blithely ignores this gaping incongruity between what the Bible plainly states vs. what they are taught by their blind guides. It would be a cruel hoax to be waiting on Him to appear if the past 100 generations of believers actually had no hope of ever seeing Him.

he will appear a second time but only to those who have been persistently waiting, listening, and obeying, Him. The face of Jesus appears in your heart:

• For God, who commanded the light to shine out of darkness, has shined in our hearts to give the light of the knowledge of the glory of God in the face of Jesus Christ. 2 Cor 4:16
• And all of us, as with an unveiled face, behold as in a mirror the glory of the Lord, and are changed into the same image from glory to glory, by the Spirit of the Lord. 2 Cor 3:18
• Blessed are the pure in heart, for they shall see God. Mat 5:8
• Beloved, now we are to be the sons of God, and it does not yet appear what we will be, but we know that when he is revealed , we will be like him, for we will see him as he is. And every man who has this hope in him purifies himself, even as He [Jesus] is pure. 1 John 3:2-3
• And this is the will of him who sent me, that everyone who sees the Son and believes in [depends on, trusts, and obeys] him, may have eternal life; and I will raise him up at the last day. John 6:40
• This is the second appearance, the revealing (revelation) of Christ, in the hearts of individual believers;
  in those who have prepared the way for him in their hearts for the Lord to enter, be revealed, and rule as Lord.
• He, who has been hidden within, is revealed. As Paul said: it has pleased the Father to reveal his Son in me, that I might preach him.
• The morning star rises in your hearts. 2 Pet 1:19
• I, Jesus.. am the root and the offspring of David, the bright morning star. Rev 22:16.
• He who overcomes, ..I will give him the morning star. Rev 2:26-28
• As the lightning comes out of the east, and shines to the west; so also will the coming of the Son of man be. Mat 24:27.
• Jesus is resurrected in us to be our true Lord. Col 2:12,3:1, Eph 2:6, Rom 6:13.
  

Grace is a process of purification, the end of which is to see Jesus bring your salvation and eternal life:

Therefore be resolute of mind, be sober, and hope to the end for the grace that is to be brought to you at the revelation of Jesus Christ. 1 Pet 1:13

But you must endure to the end. Enduring is hard because after enduring for awhile, everyone will experience trials and tribulations with suffering and persecution; some become offended and draw back — they fail to endure. Others are distracted from their dedicated seeking of God by the cares of this world, the deceitfulness of riches, the pleasures of this life, and the lusts for other things.

He only appears to those who, having obeyed his commands in love of the Lord, become pure. Jesus clearly explains this in John 14:21-24 below:

He who has my commands, and obeys them, it is he who loves me; and he who loves me shall be loved by my Father, and I will love him and will show myself to him.
Then Judas, not Iscariot, said to him, "Lord, how is it that you will show yourself to us, and not to the world?"
And Jesus answered and said to him, "If a man loves me, he will obey my spoken words; and my Father will love him, and we will come to him, and make our home with him.
He who doesn't love me, does not obey my spoken words; and the spoken words that you hear are not mine, but are the Father's who sent me. John 14:21-24

There is an entire web page on this site devoted to this second appearance: The Second Appearance of Jesus is Within the Hearts of Purified Believers.

he appears to bring salvation.

The original Greek from this verse for the word translated as salvation is swthrian, which means: deliverance, preservation, safety, salvation.
Salvation is to be delivered from all sin. Jesus appears, you see Him, to bring your salvation; the receipt of salvation is clearly seen and felt within your heart. He delivers you from all sin as you see Jesus, the God of peace, crush Satan under your feet, Rom 16:22, to destroy the residual of your sinful nature that through the Spirit you have mortified on the inward cross of self-denial.

And being made perfect, he [Jesus] became the author and source of eternal salvation to all those who heed and obey him; Heb 5:9

But he doesn't bring salvation to the whole world — only to who heed and obey him as they persistently and patiently wait for him. Salvation occurs when He appears within to bring salvation to those who have waited, listened, watched, heard, and obeyed him — those who love him, and who are kept by the power of God through faith to salvation ready to be revealed in the last time. 1 Pet 1:5. When he is revealed, we will be like him, for we will see him as he is. Everyone with this hope purifies himself, just as he is pure. 1 John 3:2-3.

“Lo! This is our God, we have waited for Him, and He will save us. This is the Lord; we have waited for him, we will be glad and rejoice and be glad in his salvation.” Isa 25:9

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