And God divided the light from the darkness.
Genesis 1:4

A believer has two principles at work within him. In his natural estate he was subject to one principle only, which was darkness; now light has entered, and the two principles disagree. Mark the apostle Paul’s words in the seventh chapter of Romans: “I find then a law, that, when I would do good, evil is present with me. For I delight in the law of God after the inward man: but I see another law in my members, warring against the law of my mind, and bringing me into captivity to the law of sin, which is in my members.” How is this state of things occasioned? “The Lord divided the light from the darkness.” Darkness, by itself, is quiet and undisturbed, but when the Lord sends in light, there is a conflict, for the one is in opposition to the other: a conflict which will never cease till the believer is altogether light in the Lord. If there be a division within the individual Christian, there is certain to be a division without. So soon as the Lord gives to any man light, he p
roceeds to separate himself from the darkness around; he secedes from a merely worldly religion of outward ceremonial, for nothing short of the gospel of Christ will now satisfy him, and he withdraws himself from worldly society and frivolous amusements, and seeks the company of the saints, for “We know we have passed from death unto life, because we love the brethren.” The light gathers to itself, and the darkness to itself. What God has divided, let us never try to unite, but as Christ went without the camp, bearing his reproach, so let us come out from the ungodly, and be a peculiar people. He was holy, harmless, undefiled, separate from sinners; and, as he was, so we are to be nonconformists to the world, dissenting from all sin, and distinguished from the rest of mankind by our likeness to our Master.

Charles H. Spurgeon, Morning and Evening

Lead me in thy truth, and teach me: for thou art the God of my salvation; on thee do I wait all the day.
Psalm 25:5

When the believer has begun with trembling feet to walk in the way of the Lord, he asks to be still led onward like a little child upheld by its parent’s helping hand, and he craves to be further instructed in the alphabet of truth. Experimental teaching is the burden of this prayer. David knew much, but he felt his ignorance, and desired to be still in the Lord’s school: four times over in two verses he applies for a scholarship in the college of grace. It were well for many professors if instead of following their own devices, and cutting out new paths of thought for themselves, they would enquire for the good old ways of God’s own truth, and beseech the Holy Ghost to give them sanctified understandings and teachable spirits. “For thou art the God of my salvation.” The Three-One Jehovah is the Author and Perfecter of salvation to his people. Reader, is he the God of your salvation? Do you find in the Father’s election, in the Son’s atonement, and in the Spirit’s quickening,
all the grounds of your eternal hopes? If so, you may use this as an argument for obtaining further blessings; if the Lord has ordained to save you, surely he will not refuse to instruct you in his ways. It is a happy thing when we can address the Lord with the confidence which David here manifests, it gives us great power in prayer, and comfort in trial. “On thee do I wait all the day.” Patience is the fair handmaid and daughter of faith; we cheerfully wait when we are certain that we shall not wait in vain. It is our duty and our privilege to wait upon the Lord in service, in worship, in expectancy, in trust all the days of our life. Our faith will be tried faith, and if it be of the true kind, it will bear continued trial without yielding. We shall not grow weary of waiting upon God if we remember how long and how graciously he once waited for us.

Charles H. Spurgeon, Morning and Evening

Our justification is the direct result of our believing the gospel; our
knowledge of our own justification comes from believing God’s promise of
justification to every one who believes these glad tidings. For there is not
only the divine testimony, but there is the promise annexed to it, assuring
eternal life to every one who receives that testimony. There is first, then,
a believed Gospel, and then there is a believed promise. The latter is the
“appropriation,” as it is called; which, after all, is nothing but the
acceptance of the promise which is everywhere coupled with the gospel message.
The believed gospel saves; but it is the believed promise that assures us of
this salvation.

Yet, after all, faith is not our righteousness. It is accounted to us in order
to (eis) righteousness (Rom 4:5), but not as righteousness; for in that case it
would be a work like any other doing of man, and as such would be incompatible
with the righteousness of the Son of God; the “righteousness which is by faith.”
Faith connects us with the righteousness, and is therefore totally distinct from
it. To confound the one with the other is to subvert the whole gospel of the
grace of God. Our act of faith must ever be a separate thing from that which
we believe.

Horatius Bonar, The Everlasting Righteousness