Believe IN HIM
John 3:16: For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life.
If you put several coats of white paint on a wall you can probably be accurate if you say that the wall is white. If you put one barely visible spot of black ink on that wall you can no longer accurately say that the wall is white.
Mixing faith in Christ with faith in something or someone else creates a faith that is NOT in Christ. Faith in Christ plus faith in a church is NOT faith in Christ. Faith in Christ plus faith in a man is NOT faith in Christ. Faith in Christ plus faith in a ritual or a ceremony is NOT faith in Christ. Faith in Christ plus faith in good works is NOT faith in Christ. Those other things are idols. They cannot totally or partially substitute for Christ. Christ NEVER needs the help of an idol. Christ and idols NEVER function together. Attempting to mix faith in Christ with faith in an idol guarantees the absence of Christ from the equation. Faith in Christ must be 100% in Christ. If one tries to have 99% faith in Christ and 1% faith in something else he does not have faith in the REAL Jesus Christ. What he has is 1% faith in the other thing and 99% faith in a FALSE Jesus Christ. He has two idols.
People who believe they can get to God by any other way than Jesus Christ do not get to the true God.
John 14:6: Jesus saith unto him, I am the way, the truth, and the life: no man cometh unto the Father, but by me.
John 6:44a: No man can come to me, except the Father which hath sent me draw him: . . .
God The Father, God The Son and God The Holy Spirit are not idols. They are One Triune God. Faith in Jesus Christ IS faith in God the Father and God The Holy Spirit. We don*t receive the Father and the Holy Spirit as separate transactions. When we receive Christ He connects us to the Father. And The Holy Spirit is the one who spoke to our hearts and convinced us that we needed to receive Christ. When we receive Christ faith in the other two members of the Godhead is automatic. Even though we may not have mentioned them by name they are always connected to the Lord Jesus. All three persons of the Trinity are involved in the salvation of a soul and in his life forever after.
John 16:13: Howbeit when he, the Spirit of truth, is come, he will guide you into all truth: for he shall not speak of himself; but whatsoever he shall hear, that shall he speak: and he will shew you things to come.
2 John 1:9b: . . . He that abideth in the doctrine of Christ, he hath both the Father and the Son.
1 Peter 1:2: Elect according to the foreknowledge of God the Father, through sanctification of the Spirit, unto obedience and sprinkling of the blood of Jesus Christ: Grace unto you, and peace, be multiplied.