There is a sin which is always 'unto death' [1 Jn 5:16]; the sin which we have not repented. Even a saint's prayers will not be heard for the unrepented sin. The person who repents correctly does not imagine that his sins are cancelled through his own effort; but knows that through this effort he makes peace with God.
The road into the Kingdom of Heaven was made by the Lord Jesus Christ, and He was the first one who traveled it. The Bible teaches that only he who follows Jesus can reach His Kingdom. But how can one follow Him? Hear what our Savior says about this: Whoever desires to come after Me, let him deny himself, and take up his cross, and follow Me (Mark 8:34). The words whoever desires mean that Christ does not compel anyone to follow Him. He has no need of the unwilling ones, but He desires that each person freely follow Him. Consequently, only those who willingly choose the Savior's path reach the Kingdom of Heaven.
For never is a man forced into sin by another’s fault, unless he have, stowed away in his heart, matter for evil deeds. Nor is a man to be held a victim of sudden deception if at the sight of a woman’s beauty he fall into an abyss of vile lust. Rather is it that diseases of soul, deeply hidden away and lost to view, come then to the surface on the occasion of the sight.
Those who have sinned must not despair. Let that never be. For we are condemned not for the multitude of evils, but because we do not want to repent...
The kingdom of God is within us when God reigns in us, when the soul in its depths confesses God as its master, and is obedient to Him in all its powers. Then God acts within it as master ‘both to will and to do of his good pleasure’ (Phil. ii. 13). This reign begins as soon as we resolve to serve God in our Lord Jesus Christ, by the grace of the Holy Spirit. Then the Christian hands over to God his consciousness and freedom, which comprises the essential substance of our human life, and God accepts the sacrifice; and in this way the alliance of man with God and God with man is achieved, and the covenant with God, which was severed by the fall and continues to be severed by our willful sins, is re-established. This inner alliance is sealed, confirmed, and given the strength to maintain itself by the power of grace in the divine sacrament of baptism, and for those who have fallen after baptism, in the sacrament of repentance: and afterwards it is constantly strengthened by holy communion. All Christians live thus; and consequently they all bear the kingdom of God within themselves, that is to say they obey God as King and are ruled by God as King.
St. Gregory the Dialogist wrote about what price we have to pay to acquire the Kingdom of Heaven. It has no exact price. Everyone has to give everything he has. The Apostle Peter gave his nets & received the heavenly kingdom; the widow gave two mites; whoever has a million dollars, let him give that; & whoever has nothing, let him give his freedom.
The only thing God requires of us is that we do not sin. But this is achieved, not by acting according to the law, but by carefully guarding the divine image in us and our supernal dignity. When we thus live in our natural state, wearing the resplendent robe of the Spirit, we dwell in God and God dwells in us. Then we are called gods by adoption and sons of God, sealed by the light of the knowledge of God.
Everything must be directed towards acquiring the Kingdom of God and fulfilling Christ's Gospel. True Christianity does not consist in intellectual abstract deliberations and teachings; rather, it is incarnate in life itself. Christ descended to earth not to instruct people in new forms of knowledge, but to call them to a new life. During our earthly life we prepare ourselves for eternity.
Greater therefore is the rejoicing of heaven over the sinner converted than upon the soul that remained just. A captain in battle will feel a warmer regard for the soldier who at first faltered and ran, and then had bravely fought back, than over the one who had never yielded yet had never thrust bravely forward. So will the farmer love more the fields that cleaned of their weeds now bear a fruitful yield, than the land which had never known thorns, yet had never yielded a bountiful crop.
Compunction comes when you consider how much you have grieved God Who is so good, so sweet, so merciful, so kind, and entirely full of love; Who was crucified and suffered everything for us. When you meditate on these things and other things the Lord has suffered, they bring compunction.
Sin, to one who loves God, is nothing other than an arrow from the enemy in battle. The true Christian is a warrior fighting his way through the regiments of the unseen enemy to his heavenly homeland.