Finding Religion is not the Kingdom of God; even Christianity which has being reduced to a religion. You can still be in any Christianity and still be spiritually hungry or empty just like the other religious. Therefore you must love all the other religious people, why instead of hating them or being against them we should feel sympathy for them, because they are trying to find the kingdom without their knowledge.
That why Jesus says Mat 11:28 Come unto me, all ye that labour and are heavy laden, and I will give you rest. Because Jesus has what man are looking for.
Let looks at Nicodemus, he was one of the most religious man and his religious was Judaism (Pharisee) who believe in Old Testament. They knew all the Law of Moses matter fact he was their main prophet, and they claim the fatherhood of Abraham. The Judaism religion is the most biblical religious we know and yet Jesus said to Nicodemus who was the head of synagogue and Jesus told him he still not in the Kingdom.
Nicodemus was the preacher in the temple; he knew the whole Old Testament bible from Genesis to Malachi and yet he was not certified. He woke up at 0200 at night and he knocked the door and said I come to see Jesus.
Joh 3:1 There was a man of the Pharisees, named Nicodemus, a ruler of the Jews:
Joh 3:2 The same came to Jesus by night, and said unto him, Rabbi, we know that thou art a teacher come from God: for no man can do these miracles that thou doest, except God be with him.
Joh 3:3 Jesus answered and said unto him, Verily, verily, I say unto thee, Except a man be born again, he cannot see the kingdom of God.
Joh 3:4 Nicodemus saith unto him, How can a man be born when he is old? can he enter the second time into his mother’s womb, and be born?
Joh 3:5 Jesus answered, Verily, verily, I say unto thee, Except a man be born of water and of the Spirit, he cannot enter into the kingdom of God.
Joh 3:6 That which is born of the flesh is flesh; and that which is born of the Spirit is spirit.
Joh 3:7 Marvel not that I said unto thee, Ye must be born again.
Joh 3:8 The wind bloweth where it listeth, and thou hearest the sound thereof, but canst not tell whence it cometh, and whither it goeth: so is every one that is born of the Spirit.
Joh 3:9 Nicodemus answered and said unto him, How can these things be?
Joh 3:10 Jesus answered and said unto him, Art thou a master of Israel, and knowest not these things?
Joh 3:11 Verily, verily, I say unto thee, We speak that we do know, and testify that we have seen; and ye receive not our witness.
Joh 3:12 If I have told you earthly things, and ye believe not, how shall ye believe, if I tell you of heavenly things?
According to the above conversation between Jesus and Nicodemus we see even Judaism religious is a search for the kingdom and still Jesus said he must be born again and receive the spirit of the King and you shall be saved.