Do you believe that one's personal confession, during his/her prayer time, without the presence of a priest, is just as valid in terms of receiving forgiveness of sins. Or, does the presence of the priest make all the difference in whether we receive the sacrament of repentance or not?
As I said in my reply, I don't have a short answer yet. So let's explore it together.
First things first. All sacraments require the presence of at least one other person, because all sacraments comprise of a material and spiritual component, without either, would not be a valid sacrament. The theologians or more philosophical Catholics call it the "matter" and "substance", I think.
As mentioned in my reflection on confession, there is mortal sin and, well, not-so-mortal sin which is called "venial sin". Mortal sin is the one that you have to go for confession, because it means that you are no longer in communion with Christ and with the church.
Now I need to digress a bit, but it is completely relevant to the question.
The relationship between Christ and his Church is one of marriage – Christ is married to his church. And married couples are called to love after this example, where Christ, the bridegroom, gives himself totally to his bride, even to the point of laying his life down for his bride. The bride, on the other hand, receives her bridegroom totally as a bride should, and places herself under the mission of her bridegroom. That mission, of course, is to love the bride.
Pope John Paul II has given us the Theology of the Body which explains this more clearly. Okay, not more clearly, but more deeply. Christopher West is the one who explains the Pope's teaching more clearly in his books, like "Theology of the Body for Beginners".
But we don't need the Pope's theology to understand the answer to this question. We can refer to scripture where it says "a man must leave his father and mother and be joined to his wife, and the two will become one body". (Matthew 19:5).
(I digress a bit here, in case you don't like scripture references. We can always appeal to natural law. Just by observing marriages in real life, we can see that the best marriages work out when the husband does not cling to his father and mother and chooses his wife over them.)
And we look at the person of Jesus, how he left his heavenly father and earthly mother, and was joined to his bride through his life, death and resurrection. And the two – Christ and his church – became one body, and still remains one body.
Now back to our question. The sacrament of reconciliation reconciles a sinner back to Christ and to the church. It is not possible for a person to be in communion with Christ and not with the church, or be in communion with the church but not be with Christ, simply because Christ and his church are one.
Sin is the state in which a person is separated from Christ (and his church); the sacrament reunites him with Christ (and his church).
However, this applies only to mortal sin, in which a sinner is completely separated from Christ and his church. It does not apply to venial sin.
To reiterate what was written in a previous question (Is having wet dreams a sin?),
There are three conditions that must be fulfilled before a person is considered to have committed a mortal sin:
1. Freedom of choice – a person must have been able to make the choice before an act is considered a sin. Coercion to make that choice lessens the seriousness of the sin.
2. Gravity of sin – the act must be a grave matter.
3. Fullness of knowledge – the act was committed with the sinner's full knowledge of the gravity of the sin, and his or her deliberate consent.
Venial sin is sin whose object is a grave matter but committed without full knowledge of the gravity or without full consent. In other words, there is actually no sin that is not considered grave.
So, in answer to your question, Steve, one's personal confession during his/her prayer time, without the presence of a priest is valid, provided the sin is not a mortal sin, that is, one that has severed the relationship between the sinner and Christ (and his church). But this forgiveness of sins is not considered a sacrament.