“Out of the mouths of babes.” The idea is that children usually tell the raw truth, at least as they understand it, because their worldview has not yet been compromised by adult desire and self-deception. Consider the words from a “child's” song: “Jesus loves me, this I know, for the Bible tells me so.” In contrast, consider the “adult” song about the resurrected Christ: “You ask me how I know he lives, he lives within my heart.” The former is based on the objective truth of Scripture (“the Bible tells me so”), the latter on the subjective experience of the believer (“he lives within my heart”).
What's wrong with feeling Jesus in my heart? Nothing, as long as what I ‘feel’ is rooted in truth determined by the Bible. The writers of Scripture made this abundantly clear: “I write this to you who believe in the name of the Son of God, that you may know that you have eternal life” (1John 5:13). The Bible was written to reveal certain spiritual truths bringing readers to knowledge and faith in those truths. This rather simple process need not be muddled by human wisdom and/or experience. The child-like faith Jesus praised expresses itself in humble submission to God's word (Matthew 18:3; Isaiah 66:2).
Does this mean I am not to have feelings about the Lord? God forbid! However, those feelings are to be built upon what God reveals in Scripture. How do I know Jesus loves me? The Bible tells me so. How do I know he lives? The Bible tells me so. How do I feel? Great!