Question: "Are children always a blessing from God?"
Answer: The scriptures are very clear that God is present in the creation of every human life. The most vivid depiction of this is seen in Psalm 139:13-18. The fact that God sovereignly superintended David's creation caused him to praise God. David also pointed out the fact that God had the details of his life planned before eternity. In Jeremiah 29:11 God confirms David's thoughts, "For I know the plans I have for you," declares the Lord, "plans to prosper you and not to harm you, plans to give you hope and a future." Of course this brings up a very good question. What about those conceived out of rape or illegitimacy? The parent or parents that are responsible for that child may not "feel" as though that child is a blessing from God, but how that child was conceived does not mean that God did not sovereignly superintend its formation in the womb as David speaks of. God has a plan and purpose for every person born regardless of how that birth came about. If this were not so then the Scripture would not have said so. In the New Testament we read that God loves us so much that He sent His Son to die for us (John 3:16).
This love is the same love that compelled the Savior to teach the disciples God's Word and to demonstrate God's love for us through His death and resurrection (1 John 4:7-8). There is no end to how much God loves us and desires to bless us. The intention of God in the creation of man was to have fellowship with Him. First John 4 tells us that once we recognize this, it enables us to love others. Whether we view every child as a blessing from God depends on how much we see that child as God sees them. When we look at each child through the eyes of God, there is no question that every one is a blessing from Him. If we look at that child through the eyes of sin, then we would doubt that blessing because we focus on the creature and not the Creator.
It is God's plan and desire that each child be born according to His plan for us and that is through marriage. When that does not happen, it does not exclude that fact of God's love and care for the child. David concluded in Psalm 139:17 that God's thoughts for his people were indeed precious and innumerable. The most practical application of this is seen in the lineage of Christ in Matthew 1. All through the names we recognize those who failed in life in some way and see those who were born of illegitimacy and sin. This fact did not disrupt the fact that God's Word was fulfilled and brought the blessing of salvation to Man.