There are Many Seed Planters
Many of our Christain friends have also planted a good seed. "They have planted the seed of the Word of God according to their understanding, and that seed has swollen and grown into a beautiful tree in their lives. This is not the tree of the fullness of the Gospel of Christ, yet it is a good tree. Since they have never seen a better tree, they believe that it's the best there is.
"Before these people will be interested in responding to the fullness of Christ's Gospel, they will need to get some glimpses of that fullness. We must give them the opportunity to see our tree. Many have been told that ours is an evil, even a 'pagan' tree. We must help them to understand that ours is a very good Christian tree: the true tree of life on which the fruits of the Spirit, even the fulness of the fruits of the atonement, are found growing in abundance. Then we must leave it in our Father's hand. They are His children and He knows them and will bless them according to His plan and their ability to receive. Remember, HIS PLAN for these children may be different from our plan for them."
From Understanding These Other Christians, by Richard G. Grant, p. 237.