UPDATE:
Also, in looking at (i.e. reading about) the differences between Catholic baptism and Protestant baptism, is it safe to say/explain to my children that Catholics believe that ordinarily the Holy Spirit is infused at baptism and that faith results from having the Holy Spirit (i.e., it is what God does for me through the minister of baptism) instead of the mainline Protestant view that we get baptized (i.e., do something for God) because the Holy Spirit already dwells in us (i.e.,because of what He has already done for me)?
How would you suggest explaining this to children?
This is what I teach to the children that God has entrusted me too at my church - I am always mindful of what Jesus says to those who “teach” – we will be held more accountable than non-teachers because we are handing on the deposit of faith and we can never teach anything that is contrary to the Gospel of Jesus. Adults need to be reminded of this as well and also what is salvation, faith and what is Baptism and what did it do to my soul and why is Baptism important as most if not all were baptized as infants or young babies.
Our relationship with God is a process and one that develops over time. This “salvation” that God is offering to all men (not just us Christians, but non-Christians, Jews, Muslims, Buddhist, and even the atheist) is a gift and so is faith. Salvation is also a two-part plan of God. God became man and took on human flesh, human form in order to save us from our sins. He offers this salvation to everyone who was born, is born now and those who are yet to be born. We cannot save ourselves. Buddha cannot save you either. Only Jesus can.
But, our relationship with God is one that develops over time. Faith can be compared to seeds. Seeds planted in a garden will only grow into a plant and bear fruit with proper water, light and nutrients and if we want to harvest the fruit we have to protect the plant from invasion of pests. Seeds of Grace are very much like those garden seeds. The faith that your children have now hopefully grows and increases. We are called to participate in our salvation and our faith.
We are all born without the supernatural life of God in our souls due to Original Sin. Baptism opens our souls to receive the very life of God Himself in us. Baptism is an indelible mark on your soul and it can never be removed even if you reject God - you will bear the sign of a Christian for all eternity but separate from the love of God. Baptism can’t be repeated as Scripture states there is One Lord, One Baptism and One Faith. Baptism does what it says that it does - We are put in right relationship with God due to the rupture of that first sin. Water is the sign of Baptism. Jesus was baptized not because he needed forgiveness of sin but in order to purify the waters of Baptism and put His Power His Holy Spirit in the water to give us new life. What better time to signify Baptism than when a baby is born. Since God offers this Gift of Himself to ALL men, and the only requirement is openness - what a beautiful gesture to God to give back to Him what He has given to us. And who is more open than an infant? There is no actual sin, just OS, there is no refusal, just openness. In an infant baptism the child takes on the faith of their parents and godparents made in proxy. That means they have made a promise before God that they will teach their children about who He is. The children do have to make a profession of faith at some point in their life. Baptism is also prefigured in the OT thru the saving of Noah and his family (Gen. 7:12-23, see also 1 Peter 3:20-21) and Moses crossing of the Red Sea during the Exodus (Ex. 14:1-22).
Also its good to point out what exactly is a Sacrament. A Sacrament is an outward sign instituted by Christ to give inward Grace (Himself). God gives Himself and we participate with eyes of faith by placing Him in our hearts and souls where no one can take Him from us. That is why He gives Himself (Body, Blood, Soul and Divinity) in the Eucharist to nourish us - The Eucharist is food for our soul. Or food for the journey home to Heaven. Manna in the OT is a pre-figurement of the Eucharist in the NT.
Also Sacrament means oath. According to ancient Israel in order to enter into a covenant one must swear an oath. God relates to us by means of covenants. So if we are to enter into a right relationship with God, we need to enter into a covenant - by means of an oath - a Sacrament is the New Covenant.
In the New Covenant, the one Jesus established between man and God thru His once for all redemptive work, people come into relationship with God by means of an oath. The first oath is what we name Baptism. This relationship with God thru Jesus is then renewed thru other oaths such as by receiving the Holy Eucharist.
Sacraments are not just experiences, symbols or signs. Rather they are powerful instruments of His Grace whereby God grants and infuses His Divine Life within the human soul transforming us into His sons and daughters (it is nothing we have done - but Everything that HE has done) We participate in this life of Grace by meeting God with our faith.