Mark 16:15-18
And He said to them, "Go into all the world and preach the gospel to every creature. He who believes and is baptized will be saved; but he who does not believe will be condemned. And these signs will follow those who believe: In My name they will cast out demons; they will speak with new tongues; they will take up serpents; and if they drink anything deadly, it will by no means hurt them; they will lay hands on the sick, and they will recover."
This is the Great Commission that Jesus has given to all the believers.
In verse 16 Jesus says, "He who believes and is baptized will be saved". Believes in what? - A religious organization? Our works with which we aim to earn God's favor? The answer is in verse 15. "Go into all the world and preach the gospel to every creature." Believe the Gospel - the Good News that Jesus provided an eternal redemption for us (Heb 9:12), that He wiped off the handwritten ordinances that stood again us (Col 2:14), that He annihilated the power of the enemy (Col 2:15), that He delivered us from all bondages (Luke 4:18-19) and provided absolute liberty to all.
Verses 17 and 18 says, "And these signs will follow those who believe: In My name they will cast out demons; they will speak with new tongues; they will take up serpents; and if they drink anything deadly, it will by no means hurt them; they will lay hands on the sick, and they will recover."
This is not something that we can earn with our self-effort. The only qualification needed is found in verse 17 - "those who believe". And here is the best part - the burden of saving, changing, healing or delivering the whole world is not on our shoulders! When we do our part, which is believe and yield to the Holy Spirit's directions, we become effective channels for the Lord to works with us and through us to confirm the word through the accompanying signs (Mark 16:20, Philippians 2:13).
For meditation:
Colossians Chapters 1 and 2
Hebrews Chapters 9 and 10