The seven sacraments are the primary vehicle through which God conveys grace. However, being almighty and powerful, He is not limited to the sacraments.
For example, those without the light of faith receive grace in different ways. This is part of the universal salvific will of Christ—when Christ died for humanity it was not limited to specific time. Rather, He died for all: past, present, and future. God, who exists outside of time, knows all. Therefore, when our Blessed Savior hung upon the cross and shed His precious blood for humanity, He consciously did so for all those in the future as well.
There is a theological concept known as the “anonymous Christian.” This means that if a person through no fault of his own did not consciously and deliberately reject Jesus Christ and His one true Church, and if that same person follows his faith to the best of his ability according to held beliefs, then by the merits of Christ on the cross, he can still be saved. He is only accountable for that which he knows.
The old axiom, “The more you know the more you are held accountable,” is different from American law in which you are accountable for every law known or unknown to you. God is more merciful. However, once you receive the light of faith in Christianity and do not do anything about it, then all things change. Conversion is absolutely necessary once you receive the grace of enlightenment.
Missionaries are important because the Church is not satisfied with “anonymous Christians.” The Church wants everyone to have a conscious relationship with the Lord who saves and continues to bless them through the sacraments. While it is true God comes to us in many ways, inspirations, thoughts, and kindnesses from people, He primarily comes to us in the sacraments. Jesus Christ and His Church (the mystical body of Christ) is the primordial sacrament.
In other words, He is the way in which grace is conferred. Second, the Church is the sacrament of Jesus Christ, or the continual living vehicle for the transfer of grace. The seven sacraments are the final way that Christ bestows grace upon the Church. While a person can spiritually survive with a minimum of grace, it is like living on life support. Living a full, robust, and healthy spiritual life means accepting and cooperating with as much divine grace as God offers, day in and day out.
Sacramentals bestow actual grace (as opposed to sacraments which confer sanctifying grace), but their effect chiefly depends upon disposition of the recipient (ex opere operantis in Latin). This means a very good or holy person receives more spiritual benefit than someone who is merely just okay. Sacramentals can be objects, such as rosaries, medals, holy water, and scapulars, and they can be actions, like blessings and exorcisms.
The blessing of a priest, at the end of Mass or over a person, is a prime example of a sacramental. Sacramentals differ from sacraments since they were not instituted by Christ and they do not confer sanctifying grace.