We have no reason to fear that the Lord will not give us whatever is profitable for us, seeing that he has not spared his own Son to save us. (Geneva Bible Translation Notes)

As if he had said: What comfort may we derive from these doctrines? God has called us all to holiness, and to love to him, which is the principle of holiness.  We are persecuted and despised, it is true, and we may be more so; but, as God has called us to love him, and all things work together for good to them that love him; and, as his covenant with Abraham, while he was in his Gentile state, shows his gracious purpose towards us Gentiles, whom he has foreknown, who have been objects of his gracious foreknowledge, as well as the Jews, and who have now the fullest proof that we were so, by his sending us the Gospel, and showing us, in it, that if the Israelites were to be a holy priesthood, a royal nation, we are no less favored, as he has predestinated, from the beginning determined, that we should be conformed to the image of his Son, who is to be the first-born among many brethren, the head and chief of all converted Jews and Gentiles, and, in order to our final salvation, has called, invited us to believe on the Lord Jesus Christ, has justified those who do believe, and has glorified, highly honored, and adorned them with innumerable gifts and graces, and, if they continue to possess that faith which worketh by love, will bring them, both body and soul, to his eternal glory, their bodies being made like unto his glorious body: - seeing, therefore, all these things are so, what comfort in our tribulations shall we derive from them? - Why this: If God be for us, who can be against us?  He who is infinitely wise has undertaken to direct us: He who is infinitely powerful has undertaken to protect us:  He who is infinitely good has undertaken to save us.  What cunning, strength, or malice, can prevail against his wisdom, power, and goodness?  None.  Therefore we are safe who love God; and not only shall sustain no essential damage by the persecutions of ungodly men, but even these things work together for our good. (Dr. Adam Clarke)

What shall we then say to these things? &c. Either to these afflictions, shall we murmur and repine at them? no, since they work together for our good, and are not to be compared with our future glory, which is certain; for if we suffer with, and for Christ, we shall be glorified together:  or to these blessings just now mentioned, as the foreknowledge of God, divine predestination, effectual calling, free justification, and eternal glorification, what can be said to these? nothing can be added to them, they are a complete set of blessings, wanting nothing; nor can the greatness of them be fully expressed, or the freeness of God's grace displayed in them, sufficiently declared:  what remains for us to do, but to be thankful for them, and glory in them? or what can be said "against" them? nothing at all, they cannot be contradicted or gainsaid; they are true and faithful sayings; they can never be made void, and of no effect, by hell or earth; nor ought our unbelieving hearts to have anything to say against interest in them: or what is to be said, or inferred "from" them? why, the free, sovereign, unchangeable, and everlasting love of God, in providing and bestowing such benefits; and the certainty of salvation, which is infallibly secured hereby (Dr. John Gill)

That is good for the saints which does their souls good.  Every providence tends to the spiritual good of those that love God; in breaking them off from sin, bringing them nearer to God, weaning them from the world, and fitting them for heaven.  When the saints act out of character, corrections will be employed to bring them back again.  And here is the order of the causes of our salvation, a golden chain, one which cannot be broken.  1. Whom he did foreknow, he also did predestinate to be conformed to the image of his Son.  All that God designed for glory and happiness as the end, he decreed to grace and holiness as the way.  The whole human race deserved destruction; but for reasons not perfectly known to us, God determined to recover some by regeneration and the power of his grace.  He predestinated, or before decreed, that they should be conformed to the image of his Son. In this life they are in part renewed, and walk in his steps.  2. Whom he did predestinate, them he also called. It is an effectual call, from self and earth to God, and Christ, and heaven, as our end; from sin and vanity to grace and holiness, as our way.  This is the gospel call.  The love of God, ruling in the hearts of those who once were enemies to him, proves that they have been called according to his purpose.  3. Whom he called, them he also justified. None are thus justified but those that are effectually called. Those who stand out against the gospel call, abide under guilt and wrath.  4. Whom he justified, them he also glorified.  The power of corruption being broken in effectual calling, and the guilt of sin removed in justification, nothing can come between that soul and glory.  This encourages our faith and hope; for, as for God, his way, his work, is perfect.  The apostle speaks as one amazed, and swallowed up in admiration, wondering at the height and depth, and length and breadth, of the love of Christ, which passeth knowledge.  The more we know of other things, the less we wonder; but the further we are led into gospel mysteries, the more we are affected by them.  While God is for us, and we keep in his love, we may with holy boldness defy all the powers of darkness. (Matthew Henry)