Pilgrim, I will admit that it is not clear what David was sure of when he said "I will go to him, but he will not return to me." So it could be interpreted either way.

And as for Acts 2:39, I definitely do not believe that all of believers children will go to heaven, only those God foreknew or foreloved. I guess it makes sense to say that the children of believers that die in infancy may not be foreknown and therefore will not be glorified (Rom 8:30.

Does the same apply for the mentally retarded?