Samaritan's Purse/OCC is very definitely an evangelical organisation, and if you know that and don't mind, then there isn't a problem.
In their own words (from here:
"The shoe boxes don?t just offer physical items to make life better for children. The gifts also present an opportunity to learn about the Gospel.
That?s exactly what Ralph did. When he accepted his gift, he also accepted Christ. As he kicks a soccer ball to a friend, his smile isn?t just because of his new toys. Now he has found God?s love. Ralph and his friends were offered ?The Greatest Gift of All? booklet with their gifts, which explains the story of Christ and salvation through Him. Ralph said he is excited to learn more about Jesus. He is blessed because his mother is also a Christian, and she taught him about Christ even before he believed. Joy also received the booklet, but she didn?t look at it as soon as she received it. She said she wanted to look at it later. When she reads ?The Greatest Gift of All,? there is hope that she too will find Christ?s love".
And here:
"Children who received shoe boxes are invited to participate in TGJ by the local churches and ministry partners. TGJ is a 12-lesson discipleship program, in the local language, from Samaritan?s Purse. It is utilized by the Operation Christmas Child project and is implemented by local churches and ministry partners".
And here is their last annual report, which makes their evangelising very clear.
This is the booklet they give out with the boxes. Some quotations:
"You were planned by God; you were not a mistake. He knows you and loves you. You are very valuable to him... Dear God... Help us to remember that you made everything and are in charge of everything. Amen" (p.9)
"When you sin, the pay you get is death. Everybody sins. We can't solve our sin problem without God" (p.16)
"If we believe in Jesus it means we can be friends with God and spend Forever with him in Heaven" (p29)
"Say with your mouth 'Jesus is Lord'. Believe in your heart that God raised him from the dead. Then you will be saved" (p.30)
There is much more in the same vein. As I said, if you are yourself a Christian, much of this will not be a problem for you.
But personally, I do not want to donate to a charity whose aim is to convert people to Christianity (or any other religion), so I have not taken part in these shoebox appeals. I dislike the fact that most people don't seem to know about the evangelism, and I think schools agree to take part without knowing the facts. It makes me uncomfortable that British children are innocently and kindly giving simple presents, which this organisation then use as a 'vehicle' for evangelising.