From John Calvin’s Geneva Liturgy of 1543:
Lord God, eternal and almighty Father: We acknowledge before your holy majesty that we are poor sinners, conceived and born in guilt and in corruption, prone to do evil, unable of our own power to do good. Because of our sin, we endlessly violate your holy commandments. But, O Lord, with heartfelt sorrow we repent and turn away from all our offenses. We condemn ourselves and our evil ways, with true sorrow asking that your grace will relieve our distress. Have compassion on us, most gracious God, Father of mercies, for the sake of your son Jesus Christ our Lord. And in removing our guilt, also grant us daily increase of the grace of your Holy Spirit, and produce in us the fruits of holiness and of righteousness pleasing in your sight: Through Jesus Christ our Lord. Amen.
Adapted by M.D. Bush
From John Knox’s Liturgy of 1560:
Almighty God, we are unworthy to come into your presence, because of our many sins. We do not deserve any grace or mercy from you, if you dealt with us as we deserve. We have sinned against you, O Lord, and we have offended you. And yet, O Lord, as we acknowledge our sins and offenses, so also do we acknowledge you to be a merciful God, a loving and favorable Father, to all who turn to you. And so we humbly ask you, for the sake of Christ your son, to show mercy to us, and forgive us all our offenses. Forgive the sins of our youth, and the sins of our old age. By your Spirit, O God, take possession of our hearts, so that, not only the actions of our life, but also the words of our mouths, and the smallest thought of our minds, may be guided and governed by you. Through Jesus Christ our Lord, to whom, with you and the Holy Spirit, be all honor and glory, now and forever. Amen.
Adapted by M.D. Bush
From the 1585 Reformed Liturgy of the Palatinate:
I, a poor sinner, acknowledge before you, my God and Creator, that I have terribly and in many ways sinned against you, not only outwardly, but much more with inward blindness, unbelief, doubts, despondency, impatience, pride, covetousness, envy, hatred, malice, and other sinful affections, as you, my Lord and God, know well, and I cannot deeply enough deplore. But I repent of these things, and am sorry for them, and heartily ask you for mercy, for the sake of your beloved Son Jesus Christ. Amen.
Adapted by M.D. Bush, with this comment: This confession is of Lutheran origin. It is common in the Lutheran liturgies in Germany from the same era, and may have been held over from Heidelberg’s Lutheran days.
The Original Henry Van Dyke Confession of Sins:
Most holy and merciful Father; We acknowledge and confess in Thy Presence: Our sinful nature prone to evil and slothful in good; And all our shortcomings and offenses against Thee. Thou alone knowest how often we have sinned: In wandering from Thy ways; In wasting Thy gifts; In forgetting Thy love. But Thou, O Lord, have pity upon us; Who are ashamed and sorry for all wherein we have displeased Thee. Teach us to hate our errors; Cleanse us from our secret faults; And forgive our sins; For the sake of Thy dear Son our Saviour. And O most holy and loving Father; Send Thy purifying grace into our hearts, we beseech Thee; That we may henceforth live in Thy light and walk in Thy ways; According to the commandments of Jesus Christ our Lord. Amen.
Collected by M.D. Bush. Updated versions are commonly available.