They need to learn that first, that they need to repent and believe in Christ as their Saviour,without that they are not His.
Why don't you say plainly what you are implying?
I am just telling you what scripture says
Gal 3:26 For ye are all the children of God by faith in Christ Jesus.
Jhn 1:9 [That] was the true Light, which lighteth every man that cometh into the world. Jhn 1:10 He was in the world, and the world was made by him, and the world knew him not.
Jhn 1:11 He came unto his own, and his own received him not.
Jhn 1:12 But as many as received him, to them gave he power to become the sons of God, [even] to them that believe on his name:
Jhn 1:13 Which were born, not of blood, nor of the will of the flesh, nor of the will of man, but of God.
Rom 8:14 For as many as are led by the Spirit of God, they are the sons of God.
Eph 1:5 Having predestinated us unto the adoption of children by Jesus Christ to himself, according to the good pleasure of his will,
The only ones that can pray that prayer are those that have come in faith to Christ. To teach young people that they can call God Father based on their humanity, good works or church attendance is to teach error.