Celebrating the remembrance of our Lord's death should only be done by consecrated believers. 1 Corinthians 10:16-17, 16 "The cup of blessing which we bless, is it not the communion of the blood of Christ? The bread which we break, is it not the communion of the body of Christ? 17 For we being many are one bread, and one body: for we are all partakers of that one bread." The body of Christ means the body of the Anointed. Only consecrated Christians come under the anointing of the Holy Spirit. 

A child cannot make a decision to sacrifice his natural, earthly life to do God's will. As Jesus said, "And whoever does not bear his cross and come after Me cannot be My disciple. 28 For which of you, intending to build a tower, does not sit down first and count the cost, whether he has enough to finish it– … 33 "So likewise, whoever of you does not forsake all that he has cannot be My disciple." Luke 14:27-28, 33 (NKJV) Our vows are a vows of sacrifice. Romans 12:1, "…you present your bodies a living sacrifice…"

Children should be taught to obey God and to love righteousness. Micah 6:8 (NKJV), "He has shown you, O man, what is good; And what does the LORD require of you but to do justly, to love mercy, and to walk humbly with your God?"
This will always be required of every intelligent, living being.

However, the heavenly calling to deny self and to suffer for obediently following God is open only for the period between and including the first and second advents of our Lord. Only by proving obedient during this present evil world (Galatians 1:4) can a spirit-begotten person develop a character-likeness to our Lord. When Christ reigns, evil will eventually end. Then all will be in harmony with God. 1 Corinthians 15:25-26, 28 (NKJV), 25 "For He must reign till He has put all enemies under His feet. 26 The last enemy that will be destroyed is death. … 28 Now when all things are made subject to Him, then the Son Himself will also be subject to Him who put all things under Him, that God may be all in all."