When you say "I love you" to others you make the love of God credible and believable.
Something similar happens when it comes to God's mercy, grace and forgiveness. It's hard to experience the mercy of God. It's hard to feel forgiven. And the church doesn't help much with this. As Dietrich Bonhoeffer writes in Life Together in the church "we are not allowed to be sinners":
For the pious community permits no one to be a sinner. Hence all have to conceal their sins from themselves and from the community. We are not allowed to be sinners. Many Christians would be unimaginably horrified if a real sinner were suddenly to turn up among the pious. So we remain alone with our sin, trapped in lies and hypocrisy, for we are in fact sinners.This experience of hiding and shame is a tragedy given the grace and mercy of God. As Bonhoeffer describes, under the merciful gaze of God you are allowed to be a sinner:
However, the grace of the gospel, which is so hard for the pious to comprehend, confronts us with the truth. It says to us, you are a sinner, a great, unholy sinner. Now come, as the sinner that you are, to your God who loves you. For God wants you as you are, not desiring anything from you – a sacrifice, a good deed – but rather desiring you alone. God has come to you to make the sinner blessed. Rejoice! This message is liberation through truth. You cannot hide from God. The mask you wear in the presence of other people won’t get you anywhere in the presence of God. God wants to see you as you are, wants to be gracious to you. You do not have to go on lying to yourself and to other Christians as if you were without sin. You are allowed to be a sinner...And yet, God's mercy remains unbelievable to us. We don't trust it. It seems too incredible. And so we continue to hide in shame and fear.
This is why the sacrament of confession is so important. In being embraced as a sinner by another human being the mercy and forgiveness of God becomes credible. In confession we become sacraments of God's grace for each other and that makes the grace of God more believable. God's forgiveness becomes credible when we forgive each other. Bonhoeffer:
Now each stands in Christ’s place. In the presence of another Christian I no longer need to pretend. In another Christian’s presence I am permitted to be the sinner that I am, for there alone in all the world the truth and mercy of Jesus Christ rule. Christ became our brother in order in order to help us; through Christ other Christians have become Christ for us in the power and authority of Christ’s commandment. Other Christians stand before us as a sign of God’s truth and grace. They have been given to us to help us. Another Christian hears our confession of sin in Christ's place, and forgives our sins in Christ's name. Another Christian keeps the secret of our confession as God keeps it. When I go to another believer to confess, I am going to God...We are to become signs of God's mercy for each other. Me for you and you for me. Each of us an incarnation of God's grace and love.
I'm reminded of the exhortation from 1 Peter:
1 Peter 4.8-11
Above all, love each other deeply, because love covers over a multitude of sins. Offer hospitality to one another without grumbling. Each of you should use whatever gift you have received to serve others, as faithful stewards of God’s grace in its various forms. If anyone speaks, they should do so as one who speaks the very words of God.