Eph 2:20 . . . built on the foundation of the apostles and prophets, with Christ Jesus himself as the chief cornerstone.

The Bible says that we are built on the foundation of Jesus and the apostles.
So, To receive salvation we need to find the church, which God established and the apostles attended.

Then what truths were kept in the apostolic age?

Lk 4:16 He went to Nazareth, where he had been brought up, and on the Sabbath day he went into the synagogue, as was his custom. And he stood up to read.
Ac 17:2 As his custom was, Paul went into the synagogue, and on three Sabbath days he reasoned with them from the Scriptures. . .

Following the example of this, We,too, must go to a church that keeps the Sabbath because Jesus and the apostles kept the Sabbath.

Mt 26:17-19 On the first day of the Feast of Unleavened Bread, the disciples came to Jesus and asked. . . So the disciples did as Jesus had directed them and prepared the Passover.
Mt 26:26-28 While day were eating, Jesus took bread, gave thanks and broke it, and gave it to his disciples, saying, "Take and eat; this is my body." Then he took the cup, gave thanks and offered it to them, saying "Drink form it, all of you. this is my blood of the covenant, which is poured out for many for the forgiveness of sins."

Jesus Himself established the Passover and the apostles were keeping the Passover.
And when we see the book of Acts and John, Jesus and the apostles kept the Pentecost and the Feast of Tabernacles(Ac 2:1-4, Jn 7:2,37,39)

We can be saved when we go tho the true church that follows the truth.
Today only World Mission Society Church of God(WMSCOG) keeping the Sabbath, Passover and Pentecost and the Feast of Tabernacles.

So, the church of God is God Himself established and the apostles attended.
Let us stay in the Church of God till the end and be saved!