Monday night I shared with our students some simple Jesus Math:
Everything - Jesus = Nothing
Jesus + Nothing = EVERYTHING
If you understand those equations, you get the Gospel.
Here's some deeper wisdom on the topic from C.H. Spurgeon:
We understand the words "to save" to mean the whole of the great work of salvation, from the first holy desire onward to complete sanctification. The words are multum in parvo - much in little. Indeed, here is all mercy in one word.
Christ is not only "mighty to save" those who repent, but He is also able to make people repent. He will carry those to heaven who believe; but He is, moreover, mighty to give people new hearts and to work faith in them. He is mighty to make the one who hates holiness love it, and to constrain the despiser of His name to bend the knee before Him.
This is not all the meaning, for the divine power is equally seen in the work that follows. The life of a believer is a series of miracles brought about by the mighty God. The bush burns, but it is not consumed. He is mighty enough to keep His people holy after He has made them so, and to preserve them in His fear and love until He consummates their spiritual existence in heaven.
Christ's might does not lie in making a believer and then leaving him to shift for himself, but He who begins the "good work in you will perform it until the day of Jesus Christ" (Phil 1:6). He who imparts the first germ of life in the dead soul prolongs the divine existence and strengthens it, until it bursts asunder every bond of sin, and the soul leaps from earth, perfected in glory.
Believer, here is encouragement. Are you praying for some loved one? Oh, do not give up your prayers, for Christ is "mighty to save" (Isa 63:1). You are powerless to reclaim the rebel, but your Lord is almighty. Lay hold of His mighty arm and rouse it to put forth its strength. Does your own case trouble you? Fear not, for His strength is sufficient for you. Whether to begin with others or to carry on the work in you, Jesus is "mighty to save."
The best proof lies in the fact that He has saved you. What a thousand mercies that you have not found Him mighty to destroy!