The Cleansing Promise: (1 John 1:9) — Confession is directed vertically to God (“if we confess our sins, he is faithful…”), and He cleanses directly, completely bypassing an earthly confessional box or institutional mandate:

9 If we confess our sins, he [GOD] is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness.

Direct Access: (1 Timothy 2:5; Hebrews 4:14-16) — Christ is the only mediator; believers go straight to the throne of grace rather than through a human priest:

1 Timothy 2:5

5 For there is one God, and one mediator between God and men, the man Christ Jesus;

Hebrews 4:14–16

14 Seeing then that we have a great high priest, that is passed into the heavens, Jesus the Son of God, let us hold fast our profession. 15 For we have not an high priest which cannot be touched with the feeling of our infirmities; but was in all points tempted like as we are, yet without sin. 16 Let us therefore come boldly unto the throne of grace, that we may obtain mercy, and find grace to help in time of need.

The Priesthood of All Believers (Confessing to God Together): (1 Peter 2:5, 9; James 5:16) — While Roman Catholicism restricts the power to absolve sins to an ordained priesthood, the New Testament grants all believers direct access to God’s forgiveness and encourages mutual confession without a sacramental gatekeeper:

1 Peter 2:5, 9

5 Ye also, as lively stones, are built up a spiritual house, an holy priesthood, to offer up spiritual sacrifices, acceptable to God by Jesus Christ. 9 But ye are a chosen generation, a royal priesthood, an holy nation, a peculiar people…

James 5:16 (Often cited by Catholics to defend confession to priests, but it says mutual confession among brethren.)

16 Confess your faults one to another, and pray one for another, that ye may be healed. The effectual fervent prayer of a righteous man availeth much. 

Christ’s Once-For-All Sacrifice vs. Ongoing Absolution: (Hebrews 9:11-12; 10:11-12, 17-22) — Christ’s finished work on the cross completely dealt with sin:

Hebrews 9:11–12

11 But Christ being come an high priest of good things to come, by a greater and more perfect tabernacle, not made with hands, that is to say, not of this building; 12 Neither by the blood of goats and calves, but by his own blood he entered in once into the holy place, having obtained eternal redemption for us.

Hebrews 10:11–12, 17–22

11 And every priest standeth daily ministering and offering oftentimes the same sacrifices, which can never take away sins: 12 But this man, after he had offered one sacrifice for sins for ever, sat down on the right hand of God;… 17 And their sins and iniquities will I remember no more. 18 Now where remission of these is, there is no more offering for sin.¹⁹ Having therefore, brethren, boldness to enter into the holiest by the blood of Jesus, ²⁰ By a new and living way, which he hath consecrated for us, through the veil, that is to say, his flesh;²¹ And having an high priest over the house of God; ²² Let us draw near with a true heart in full assurance of faith, having our hearts sprinkled from an evil conscience, and our bodies washed with pure water.