Matt 28: 19 Go ye, therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Spirit, ...
They are baptizing through their TEACHING when people repent, put their trust in Jesus and get filled with the Holy Spirit.
The great commission given by Jesus to his apostles was to go out and teach all nations baptizing them in the name of the Father and in the name of the Son, and in the name of the Holy Spirit. Most people and church denominations think that this means one baptism with water in the name of three persons. That is not the case. It is three different baptisms. You are baptized in the name of the Father when He chooses you by granting the repentance necessary for salvation. You are baptized in the name of the Son when you put your faith and trust in Jesus' death for our salvation. You are baptized in the name of the Holy Spirit when you get filled with the Holy Spirit. It is when you receive the Holy Spirit that you are born again, become part of the body of Christ, and become One with the Father and Son. The Holy Spirit of God fills us with the same love that is shared by the Father and Son. Jesus said that the greatest commandment is to love God with all your heart, mind, and soul. The second is just like it. Love your neighbors as you love yourself. All the commandments are based on these two. So God has made it easier on us. If all our choices are made with love in our hearts, we will be obeying His commandments. At the end, Jesus will be presenting all of us perfect in love. Baptism is not something that we do. It is something that our God in three persons does for those He chooses.
1 Cor 1: 21 For after that, in the wisdom of God, the world by wisdom knew not God, it pleased God by the foolishness of preaching to save them that believe.
The Father chooses who will be saved by granting them the repentance which will open their hearts to believing and trusting in Jesus ( for the forgiveness of sins) and getting filled with His Holy Spirit who perfects us in love.