We understand why you feel that way...The bible explains it here for you...
Rom 8:9 But ye are not in the flesh, but in the Spirit, if so be that the Spirit of God dwell in you. Now if any man have not the Spirit of Christ, he is none of his.
Rom 8:10 And if Christ be in you, the body is dead because of sin; but the Spirit is life because of righteousness.
Rom 8:11 But if the Spirit of him that raised up Jesus from the dead dwell in you, he that raised up Christ from the dead shall also quicken your mortal bodies by his Spirit that dwelleth in you.
Rom 8:14 For as many as are led by the Spirit of God, they are the sons of God.
Rom 8:15 For ye have not received the spirit of bondage again to fear; but ye have received the Spirit of adoption, whereby we cry, Abba, Father.
Rom 8:16 The Spirit itself beareth witness with our spirit, that we are the children of God:
As you can see there's nothing complicated there...It's straightforward and easy to understand...Believing it is often another matter tho...
Yes, we are the children of God and now you know how we know it...
Would seem to me that a wise man, instead of criticizing and belittling Christians might instead want to know how he could get that confirmation for himself...
The Bible is clear. I only criticize and belittle faux Christians. I think the world of real ones.